Quizzes 2-38

Fill in the blank: Keeping all else constant, the sample mean of thirty measurements will have a margin of error that is ​​____________ the margin of error for a sample mean of three measurements. smaller than equal to larger than

smaller than

What is the first step in statistical hypothesis testing? assessing the evidence choosing the sample and collecting data stating the claims making conclusions

stating the claims

The placebo effect happens when subjects improve because they have confidence in the medical provider and hope in the medication, even when they may not be receiving the treatment.

True

The probability of an event tells us how likely it is that the event will occur.

True

The purpose of statistics is to convert data into useful information.

True

The sampling distribution of x̄ created from small random samples from a Normally distributed population is Normal.

True

The standard deviation of x̄ is equal to σ/√n

True

The symbol for the sample standard deviation is "s".

True

True or False: Power is the probability of rejecting a false null hypothesis.

True

When sampling from the population of interest, it is a good idea to have a representative sample.

True

Without random selection, we cannot appropriately apply the laws of probability to perform inference.

True

x̄ gets closer and closer to μ as n increases.

True

A university administrator obtains a report of the academic records of past scholarship athletes at the university. From the report the administrator believes that the mean GPA (grade point average) of current male scholarship athletes is 3.02. If a researcher believes that the mean GPA of male athletes is significantly different than 3.02, what type of test should be conducted? One-sided upper-tailed test One-sided lower-tailed test Two-sided test

Two-sided test

If we fail to reject a false null hypothesis, what type of error are we making? Type I error Type II error

Type II error

Which one of the following variables is categorical? Fuel efficiency of vehicles Type of cell phone service Number of phone calls made from hotel rooms Body temperature

Type of cell phone service

If we take random samples of size 75 from this population, what will the shape of the sampling distribution of x̄ be? Approximately Normal Right-skewed Left-skewed Not enough information to tell

Approximately Normal

Suppose we took samples of size 100 instead of 19. What will be the shape of the sampling distribution of x̅? Approximately Normal Slightly right skewed Slightly left skewed Normal

Approximately Normal

Suppose we took samples of size 45. What will the shape of the sampling distribution of x̄ be? Approximately Normal Slightly right-skewed Slightly left-skewed

Approximately Normal

According to the Central Limit Theorem, for random samples, what is the approximate shape of the sampling distribution of x̅ when the population distribution is non-Normal? Always the same as the shape of the population Approximately Normal if the sample size is large Always Normal, even if the sample size is small

Approximately Normal if the sample size is large

In studies of worker productivity, it has been noticed that any change in the work environment together with the knowledge that a study is underway will produce a short-term increase in productivity. This is known as Placebo effect Hawthorne effect Diagnostic bias Non-compliance

Hawthorne effect

What is the advantage of a histogram over a stemplot or dotplot? Histograms can be used for categorical data whereas stemplots and dotplots cannot be used for categorical data The actual data can still be observed in a histogram Histograms work well for very large data sets Shape, center, and spread are only applicable for histograms

Histograms work well for very large data sets

What type of bias results when people respond differently to questions asked by male interviewers than they do to questions asked by female interviewers? Undercoverage bias Nonresponse bias Response bias due to respondent lying or deliberately giving incorrect information Response bias due to question wording Response bias due to interviewer effect

Response bias due to interviewer effect

A sample is a subgroup of the population.

True

Why might the results from the study be biased? They didn't sample enough people. People may not want to admit they have used illegals drugs, resulting in response bias. They didn't randomly select participants.

People may not want to admit they have used illegals drugs, resulting in response bias.

What is the interquartile range? 3.5 2.1 1.2 1.7 0.4 2.3

2.1

Below what weight are 75% of newborn baby weights? 8.67 8.274 9.36 9.03

8.274

How large of a sample should you take in order to have a margin of error of 2 with a 95% confidence level when the standard deviation is 30? 30 864 865 3457

865

In context, what was the control used in this study? No Caffeine Caffeine 86mg of Placebo 86mg of Caffeine

86mg of Placebo

A run of ________ or more points in a row on the same side of the center line indicates an out-of-control process. 6 7 8 9

9

What is a distribution of a random variable? The range of the values of a variable as centered around the mean. The numerical values placed on a histogram at varying points about the mean. A list of possible values of a variable together with how often each value occurs. The position of a variable within an observed data set.

A list of possible values of a variable together with how often each value occurs.

This study is an example of An observational study. A randomized controlled experiment. A matched pairs experiment. Neither an observational study nor an experiment.

A matched pairs experiment.

The individual in this study is Number of revolutions. Type of drug. A rat. A swimming apparatus. A rotation of the exercise wheel.

A rat.

When the population standard deviation, σ, is unknown, we cannot compute a confidence interval.

False

Suppose the value for the t test statistic is t = 1.79. What is the p-value for a one-sided test? 0.10 < p-value < 0.20 0.10 < p-value < 0.15 0.02 < p-value < 0.025 0.025 < p-value < 0.10 0.05 < p-value < 0.10

0.05 < p-value < 0.10

Suppose we take a sample of size n = 50 from this same population, and we calculate x̅ = $2,800. How many standard deviations, (σ/ √n), away from μ is this sample mean? 0.40 0.9977 2.83 0.6554

2.83

Calculate the test statistic for this test. -25 -2.5 2.5 25

-2.5

What is the standard error of the sample mean, x-bar? 0.6 1.67 4.02 8.66

4.02

How was randomization incorporated into this study? All five varieties were randomly assigned to the five plots at each farm. The five varieties were randomly assigned to the eight farms - three varieties were planted twice and two varieties only once. It was not incorporated. The wheat seeds were not randomly selected from the population of wheat seeds.

All five varieties were randomly assigned to the five plots at each farm.

On a control chart, under what circumstance is the process ​out​ of control? A run of 9 consecutive sample means above the centerline or below the centerline. A sample mean below the lower limit. A sample mean above the upper limit. All of the above. None of the above.

All of the above

What characterizes a probability sample but not a sample of convenience? Some type of random device is used to obtain a probability sample. Their probabilities can be computed. All possible probability samples can be listed. Inferences can appropriately be made from probability samples. All of the above.

All of the above.

Two of the following statements describe a correct probability model. Which statement does not? There is a probability assigned to each event. The sum of all the probabilities is equal to one. All of the probabilities are between negative one and one.

All of the probabilities are between negative one and one.

What does the distribution of a random variable give us? The measure of the amount of deviation of the random variable about the mean A density curve whose x values are always positive All possible values of the random variable and how often they occur

All possible values of the random variable and how often they occur

Which of these allow researchers to establish that the treatments "cause" changes in the responses? An observational study An experiment

An experiment

What is the advantage of an experiment over an observational study? An experiment can be used to establish causation. Inference can only be made on experimental results. The results of an experiment will not be biased. An experiment removes all lurking variables.

An experiment can be used to establish causation.

We want to test the hypotheses H​0:​ μ = 50 versus H​a:​ μ > 50 to determine whether a new variety of corn will yield more than 50 bushels per acre. We plan to sample 100 plots and measure yield per acre on each plot. Assuming H​0​ is true and that σ = 5, describe the sampling distribution of x̄. Right skewed. Standard Normal. Approximately Normal with mean 50 and standard deviation 5. Approximately Normal with mean 50 and standard deviation 0.5 Unknown because we do not know the shape of the distribution of yield of corn.

Approximately Normal with mean 50 and standard deviation 0.5

What type of graph would work best for displaying the gender of babies born in March? Bar graph Histogram Stem plot Boxplot

Bar graph

What is the quantity z*? Margin of error Confidence multiplier Point estimate Standard deviation

Confidence multiplier

Which one of the following is NOT a principle of proper experimentation? Randomly allocating experimental units to treatments. Confounding the explanatory variable and response variable. Replication to measure overall experimental error and increase precision. Use of control group to determine whether treatment really works.

Confounding the explanatory variable and response variable.

The weekly oral dosage of anabolic steroids was measured on a sample of 20 body builders. Consider the following confidence interval interpretation: "We are 95% confident that the average weekly oral dose of anabolic steroids used by all body builders is between 152 mg and 194 mg." Is this interpretation of a confidence interval correct or incorrect? Why or why not? Incorrect. It does not give the actual confidence interval Correct. It gives all three parts of confidence interval interpretation Incorrect. It does not state that the value of the population parameter is in the confidence interval Incorrect. It does not give the level of confidence correctly

Correct. It gives all three parts of confidence interval interpretation

Which of the following is NOT a step of hypothesis testing? Making conclusions Assessing the evidence Creating an interval estimate Stating the claims Choosing a sample and collecting data

Creating an interval estimate

When comparing the z-distribution and the t-distribution, the t-distribution has a narrower spread.

False

Lurking variables can be managed by each of the following except one. Which is NOT a method for managing lurking variables? Using a control group with a placebo as a comparison for the treatment group. Randomly allocating experimental units to the treatments. Designing the study so that the lurking variables are confounded with the explanatory variable. Forming blocks to remove the variability associated with lurking variables.

Designing the study so that the lurking variables are confounded with the explanatory variable.

Students at a particular university are able to evaluate professors on a five point scale (a score of 1 meaning poor teaching and a score of 5 meaning excellent teaching, with answers limited to a whole number). What type of random variable is professor evaluation an example of? Discrete Continuous It is impossible to say given the information provided

Discrete

Probability samples are samples selected in such a way that Each member of the population has an equal chance of being selected. All samples of size n have the same chance of being selected. Each member of the population has a chance of being selected and that chance can be computed. The sample is guaranteed to duplicate the entire population.

Each member of the population has a chance of being selected and that chance can be computed.

ACT scores are Normally distributed with a mean of 21 and a standard deviation of 6. SAT scores are Normally distributed with a mean of 510 and a standard deviation of 100. Emma scored 646 on the SAT and Tess scored 26 on the ACT. Who has the better score? (Hint: compare z-scores.) Emma Tess

Emma

The following situation applies to the next five questions: Suppose we have a very right skewed population distribution where μ = 80 and σ = 20. For random samples of size n = 100, what is the mean of the sampling distribution of x̅? Less than 80 Equal to 80 Greater than 80

Equal to 80

Suppose Ezra's z-score is 1.50 and Gwen's z-score is 1.20. If we assume that both assessments measure the same kind of ability, who did better: Ezra or Gwen? Gwen Ezra Ezra and Gwen did equally as well as each other We do not have enough information to determine who had the higher score

Ezra

Suppose the p-value is 0.0677. At α = 0.05, what should the researcher conclude? Reject the null hypothesis. The average time full-time corporate employees work per week is greater than 40 hours. Reject the null hypothesis. The average time full-time corporate employees work per week is 40 hours. Fail to reject the null hypothesis. The average time full-time corporate employees work per week is 40 hours. Fail to reject the null hypothesis. There is insufficient evidence to conclude that the average time full-time corporate employees work per week is greater than 40 hours.

Fail to reject the null hypothesis. There is insufficient evidence to conclude that the average time full-time corporate employees work per week is greater than 40 hours.

95% of all possible x̄'s will be within 2σ of μ.

False

A z-score tells us what percentage of our data is below or above the mean.

False

If the probability of obtaining our sample data, assuming the null hypothesis were true, is large, we have enough evidence to accept the null hypothesis.

False

Which one of the following is ​NOT​ a correct statement about margin of error? A small margin of error says that we have pinned down the parameter quite precisely. For fixed level of confidence, increasing the sample size, n, reduces the margin of error. For fixed sample size, decreasing level of confidence increases the margin of error. To obtain a smaller margin of error without increasing sample size, you must be willing to accept lower confidence.

For fixed sample size, decreasing level of confidence increases the margin of error.

Which alternative hypotheses will allow you to determine statistical significance at α = 0.05 using a 95% confidence interval? H a: μ = 30 H a: μ ≠ 30 H a: μ > 30 H a: μ <30

H a: μ ≠ 30

In order to assess the evidence provided by the sample data, what is the appropriate question to ask? How likely is it to observe a difference of 0.09 or more extreme if there is no difference in the mean GPA for male and female scholarship athletes? How likely is it to observe a difference less than 0.09 in the mean GPA of male and female scholarship athletes? How likely is it to observe a mean GPA difference of 0.09 between male and female scholarship athletes? How likely is it to observe no difference in the mean GPA of male and female scholarship athletes?

How likely is it to observe a difference of 0.09 or more extreme if there is no difference in the mean GPA for male and female scholarship athletes?

The distribution of a random variable shows all possible values the random variable could take and how often they occur.

True

Consider the following confidence interval interpretation: "90% of the time the true proportion of students who get hit by a car while walking to school will fall between 0.04 and 0.12." Is this interpretation of a confidence interval correct or incorrect? Why or why not? Correct. It gives the three parts of a confidence interval interpretation. Incorrect. It does not state that the value of the population parameter is in the confidence interval. Incorrect. It does not state the confidence level correctly. Incorrect. It does not give the actual confidence level.

Incorrect. It does not state the confidence level correctly.

Twenty-five right-handed men were tested to compare their right hand strength with their left hand strength using a bathroom scale. For each male, a coin was tossed. If it landed heads, the man first squeezed the scales with his right hand and then with his left hand. If the coin landed tails, the man squeezed the scales with his left hand first and then with his right. The weight registered on the scale is recorded for both hands. What type of study is this? Matched pairs experiment Completely random experiment Observational study Simple random sample

Matched pairs experiment

Which one of the following is NOT affected by outliers? Mean Median Standard Deviation Range

Median

The five number summary consists of the following five numbers: Minimum, Q1 , mean, Q3 , maximum Minimum, Q1 , median, Q3 , maximum Minimum, μ-σ, mean, μ+σ, maximum Minimum, μ-σ, median, μ+σ, maximum

Minimum, Q1 , median, Q3 , maximum

Does this study incorporate randomization?

No

Suppose you have played a game many, many times — winning sometimes and losing sometimes. Can you use the results of playing the game to predict with absolute certainty whether you will win the game on the next try?

No

Do you need to apply the Central Limit Theorem to compute the probability on the mean weight of 16 randomly selected bags described in the above question? No, because the individual was not randomly selected. No, because the distribution of weights is Normally distributed. Yes, because we used the standard Normal table. Yes, because the sample was random and n was large.

No, because the distribution of weights is Normally distributed.

The following scenario applies to questions 8-10: The Daily Universe wanted to know the percentage of BYU returned missionaries who married within a year of returning from his/her mission. 10 students were randomly surveyed and their responses were recorded. They report their 98% confidence interval to be (0.55, 0.75). Is this a valid confidence interval? No, because it was a survey Yes, because the sample was random No, because the sample size was too small Yes, because there was a big enough sample size

No, because the sample size was too small

A university professor does not believe that there is really a difference between the GPA of male and female scholarship athletes, so he looks into how the sample was collected. His investigation shows that the study was given to all of the athletes on the basketball teams exclusively. Based on this information, should the university administration trust the results from this study? No, because not every scholarship athlete part of the study Yes, because a large enough sample was taken Yes, because the results were significant No, because the study was not taken from a random sample of scholarship athletes

No, because the study was not taken from a random sample of scholarship athletes

Interviewers were contacting the people who had been selected in a stratified sample. Many of the people they contacted refused to answer their questions. What type of bias is this? Non-response bias Undercoverage bias Interviewer bias Question wording bias

Non-response bias

Use this information to answer the next three questions. Suppose we have an extremely left-skewed population with a mean of 45 and a standard deviation of 7. For random samples of size 15, what will the shape of the sampling distribution of x̄ be? Approximately Normal Not Approximately Normal—the Central Limit Theorem does not apply.

Not Approximately Normal—the Central Limit Theorem does not apply.

With a p-value of 0.287, what is the appropriate conclusions to make? Our data provides strong evidence against H0 Our data provides strong evidence for accepting H0 Our data does not provide strong enough evidence for rejecting H0 Our data does not provide strong enough evidence for accepting H0

Our data does not provide strong enough evidence for rejecting H0

Suppose the student analyzes the data and finds that the probability of obtaining this difference (17.4 - 20), if the true mean actually is 20 minutes, is 0.012. What is the appropriate conclusion at α = 0.05? Our data provides strong evidence for accepting H0. Our data provides strong evidence for rejecting H0. Our data does not provide strong evidence for rejecting H0.

Our data provides strong evidence for rejecting H0.

All of the following are true statements about the p-value except one. Which statement is false? P-value is the area in the tail of the sampling distribution defined by H​0.​ The smaller the p-value, the greater the evidence for the alternative hypothesis. The larger the p-value, the greater the agreement between the data and H​0.​ P-value is used to determine the significance level.

P-value is used to determine the significance level.

Which graph is not used to display quantitative data? Histogram Pie chart Stem and leaf plot Dot plot

Pie chart

In order to estimate the mean age to be diagnosed with diabetes, a researcher takes a sample and finds the mean age to be 16.4. What type of statistical inference is this? Point estimation Interval estimation Hypothesis testing

Point estimation

Use this scenario to answer the next three questions. Researchers want to estimate the amount of time teenagers spend watching television during one week. A random sample of 500 teenagers yielded a sample mean of 12.60 hours of television per week. What type of statistical inference is being used? Point estimation Interval estimation Hypothesis testing

Point estimation

Which one of the following is ​NOT​ part of the definition for ​p​-value? Probability that the null hypothesis is true. Probability of obtaining a value of the statistic. The value of the statistic is farther from the claimed parameter value than the observed statistic. The null hypothesis is assumed to be true.

Probability that the null hypothesis is true.

In an email survey, students were asked, "During the past week, how many nights did you go to sleep past midnight?" What type of variable is "number of nights going to sleep past midnight"? Quantitative Categorical

Quantitative

Assume that this study is a two-sided test. A 95% confidence interval estimate was computed to be (787.82 grams, 804.18 grams). On the basis of this interval, at α = 0.05, what can she conclude about H0: μ = 780 versus Ha: μ ≠ 780? Reject H0 since 780 is inside the given interval. Fail to reject H0 since 780 is outside the given interval. Reject H0 since 780 is outside the given interval. Fail to reject H0 since 780 is inside the given interval.

Reject H0 since 780 is outside the given interval.

Suppose that the p-value was 0.0259. What is the appropriate conclusion to make if α = 0.05? Fail to reject H0. We have insufficient evidence to conclude that the mean concentration is different from 250 ppm. Fail to reject H0. We have sufficient evidence to conclude that the mean concentration is less than 250 ppm. Reject H0. We have insufficient evidence to conclude that the mean concentration is less than 250 ppm. Reject H0. We have sufficient evidence to conclude that the mean concentration is different from 250 ppm.

Reject H0. We have sufficient evidence to conclude that the mean concentration is different from 250 ppm.

Suppose the 95% confidence interval for the mean thickness of the circuit boards is (8.1, 11.1). What would be the correct conclusion to make for our two-sided hypothesis test at significance level 5%, given the confidence interval? Fail to reject Ho because 12 mm is included in the confidence interval; therefore, we have insufficient evidence to conclude that the mean thickness of the circuit boards is different from 12 mm. Fail to reject Ho because 12 mm is not included in the confidence interval; therefore, we have insufficient evidence to conclude that the mean thickness of the circuit boards is different from 12 mm. Reject Ho because 12 mm is included in the confidence interval; therefore, we have sufficient evidence to conclude that the mean thickness of the circuit boards is different from 12 mm. Reject Ho because 12 mm is not included in the confidence interval; therefore, we have sufficient evidence to conclude that the mean thickness of the circuit boards is different from 12 mm.

Reject Ho because 12 mm is not included in the confidence interval; therefore, we have sufficient evidence to conclude that the mean thickness of the circuit boards is different from 12 mm.

Suppose the ​p-value for the test described in the above question is 0.013 (although this is not the correct value.) What is the appropriate statistical conclusion at the .05 level of significance? Reject H​0 and conclude that the mean exceeds 6.3 times per month. Fail to reject H​0​ and conclude that the mean exceeds 6.3 times per month. Reject H​0​ and conclude that the mean does NOT exceed 6.3 times per month. Fail to reject H​0 and conclude that credit card usage has stayed the same at 6.3 times per month on the average.

Reject H​0 and conclude that the mean exceeds 6.3 times per month.

Suppose the correct p-value was 0.0129. What is the appropriate conclusion to make at α = 0.05? Reject the null hypothesis and conclude that we have insufficient evidence that the mean score is greater than 275. Reject the null hypothesis and conclude that we have sufficient evidence that the mean score is greater than 275. Do not reject the null hypothesis and conclude that we have insufficient evidence that the mean score is greater than 275. Do not reject the null hypothesis and conclude that we have sufficient evidence that the mean score is greater than 275.

Reject the null hypothesis and conclude that we have sufficient evidence that the mean score is greater than 275.

If a random sample of size 100 is taken, what would be the shape of the sample? Left skewed Approximately Normal Cannot be determined Right skewed Normal

Right skewed

All students in the US who took the ACT in 2014 had a mean score of μ = 21.0. Suppose you randomly select two samples of students from this population, and you calculate the sample mean for each. Sample 1 has a size of n = 40, and Sample 2 has a size of n = 250. Which sample is more likely to get a sample mean of 18 or less? Both samples are equally likely Sample 1 is more likely There is not enough information to answer this question Sample 2 is more likely

Sample 1 is more likely

For the sampling distribution of x̅ described in question 9, what is its shape? Slightly right skewed Approximately Normal Slightly left skewed Cannot be determined because the shape of the population is unknown

Slightly left skewed

Which one of the following statements about standard deviation is false? Standard deviation is affected by outliers. Standard deviation has no units of measure. A small standard deviation indicates data values are closely clustered about the mean. Standard deviation is always a nonnegative number.

Standard deviation has no units of measure.

Which of the following statements is true about the standard deviation? Standard deviation should be paired with the median. Standard deviation has the same units as data. Standard deviation is resistant to outliers. Standard deviation cannot be zero.

Standard deviation has the same units as data.

What is the name of the quantity (s/√n)? Standard deviation of the sampling distribution of x̅ Margin of error Confidence multiplier Standard error of x̅

Standard error of x̅

Jane, a student at BYU, decides to study opinions of BYU students concerning grading in religion classes. She obtains a roll from every religion class and randomly selects five students on each roll. This is an example of Simple random sampling. Multistage sampling. Stratified sampling. Convenience sample.

Stratified sampling.

How is ​level of confidence​ determined? From the confidence intervals. Subjectively determined by the researcher. The probability that the observed statistic falls in the confidence interval. Computed from margin of error. From the sample size: the larger the sample size, the larger the level of confidence.

Subjectively determined by the researcher.

What is the shape of the following distribution using a dotplot starting at 0 and incrementing up by 1? 1 , 2, 2, 3, 3, 3, 4, 4, 5 Left skewed Right skewed Symmetric Bimodal Uniform Cannot be determined

Symmetric

Suppose the correct answer is 56 sharks (it isn't), but the researcher can only afford to sample 25 sharks. If he wishes to maintain a 99% confidence level, what effect will this have on the resulting confidence interval? The margin of error will be smaller, resulting in a narrower interval. The margin of error will be larger, resulting in a wider interval. The margin of error will be smaller, resulting in a wider interval. The margin of error will be larger, resulting in a narrower interval.

The margin of error will be larger, resulting in a wider interval.

A random sample of size 10 was taken from a population. The sample has a standard deviation of zero. Which of the following statements must be true. The population has a standard deviation of zero. The sample mean is greater than the sample median. The ten data points in the sample are all equal in numerical value. The sample size is too small to compute standard deviation.

The ten data points in the sample are all equal in numerical value.

An article claims that teenagers on average will check their cellphones 150 times in one day. A student decides to test this claim using the hypotheses H0: μ = 150 vs. Ha: μ ≠ 150. A 95% confidence interval for the true mean is found to be (154.3, 167.5). On the basis of this interval, what should the student conclude at α=0.05? The true mean is equal to 150 since the claimed value, 150, is not in the interval. The true mean is not equal to 150 since the claimed value, 150, is not in the interval. We have insufficient evidence to conclude the true mean is not equal to 150 since the claimed value, 150, is in the interval. We cannot make conclusions for a hypothesis test given a confidence interval.

The true mean is not equal to 150 since the claimed value, 150, is not in the interval.

A statistic varies because each random sample yields a different value for the statistic.

True

Suppose the 95% confidence interval estimate for the mean monthly cost for Internet service for all Internet users is ($19.90, $21.90). Which of the following is a correct interpretation of this 95% confidence interval? We are 95% confident that the level of confidence (95%) is between $19.90 and $21.90. 95% of all Internet users pay somewhere between $19.90 and $21.90 per month for Internet service. We are 95% confident that the sample mean, $20.90, computed from the monthly costs for the 100 Internet users is between $19.90 and $21.90. We are 95% confident that the mean monthly cost for Internet service paid by all Internet users is between $19.90 and $21.90. The probability that the mean monthly cost for Internet service paid by all Internet users is between $19.90 and $21.90 is 0.95.

We are 95% confident that the mean monthly cost for Internet service paid by all Internet users is between $19.90 and $21.90.

Suppose the researchers compute the confidence interval as (0.3856, 0.4353). What is the correct interpretation of this interval? 98% of young adults fall between 0.3856 and 0.4353. There is a 98% probability that the true proportion of young adults who aren't registered to vote is between 0.3856 and 0.4353. We are 98% confident that the proportion of young adults in this sample who aren't registered to vote is between 0.3856 and 0.4353. We are 98% confident that the true proportion of young adults in America who aren't registered to vote is between 0.3856 and 0.4353.

We are 98% confident that the true proportion of young adults in America who aren't registered to vote is between 0.3856 and 0.4353.

Which one of the following variables is quantitative? Car color Brand of detergent ID number of a BYU student Weight of a football team member

Weight of a football team member

Use this information to answer the next six questions. For many years, "working full-time" has meant working 40 hours per week. Nowadays it seems that corporate employers expect their employees to work more than this amount. A researcher decides to investigate this hypothesis. The null hypothesis states that the average time full-time corporate employees work per week is 40 hours. The alternative hypothesis states that the average time full-time corporate employees work per week is more than 40 hours. To substantiate his claim, the researcher randomly selected 40 corporate employees and finds that they work an average of 43 hours per week with a standard deviation of 9.6 hours. Are the conditions for this test met? Why or why not? No, because it was not a random sample No, because n<30 Yes, because it was a random sample and n>30 Yes, because it was a random sample and np<10 and n(1-p)<10

Yes, because it was a random sample and n>30

Use this information to answer the next two questions: A recent study by Pew Research randomly sampled 456 working adults ages 18-34 and asked them if they were dissatisfied with their job. Of the adults sampled, 234 said "yes." Is the sample size large enough to compute a confidence interval for the proportion of adults ages 18-34 who are dissatisfied with their job? Yes, because more than 10 people said "yes." Yes, because more than 10 people said "no." Yes, because the sample size is greater than 30. Yes, because more than 10 people said "yes" and more than 10 people said "no." No, because the number of successes and number of failures do not exceed 10.

Yes, because more than 10 people said "yes" and more than 10 people said "no."

Suppose we take a sample of size n = 100 from this same population. Can we compute the probability that x̅ is greater than $2,800? Yes, because the Central Limit Theorem applies. Thus, the sampling distribution of x-bar is normally distributed. No, because the population is not normally distributed. Thus, the sampling distribution of x-bar is not normally distributed. Yes, because the population is normally distributed. Thus, the sampling distribution of x-bar is normally distributed. No, because we cannot apply the Central Limit Theorem. Thus, the sampling distribution of x-bar is not normally distributed.

Yes, because the Central Limit Theorem applies. Thus, the sampling distribution of x-bar is normally distributed.

Suppose we take a sample of size n = 10 from this same population. Can we compute the probability that x̅ is greater than 75? No, because we cannot apply the Central Limit Theorem. Thus, the sampling distribution of x-bar is not normally distributed. Yes, because the population is normally distributed. Thus, the sampling distribution of x-bar is normally distributed. No, because the population is not normally distributed. Thus, the sampling distribution of x-bar is not normally distributed. Yes, because the Central Limit applies

Yes, because the population is normally distributed. Thus, the sampling distribution of x-bar is normally distributed.

Which one of the following does NOT have the same units of measure as the data? Mean Standard deviation Interquartile range Z-score

Z-score

The purpose of a confidence interval is to provide information about the range of data in a distribution. a measure of the confidence we can have in our sample results representing the population. a list of all possible values of the statistic from all possible samples. a range of plausible values that a parameter could take.

a range of plausible values that a parameter could take.

If we fail to reject the null hypothesis, we could be making a type I error. a type II error. either a type I and a type II error. no error. An error is only made when we accidentally reject the null hypothesis.

a type II error.

What is the best measure of center for the stemplot? about 660 about 700 about 750 about 780

about 700

The announcer on the radio tells listeners that the probability of snow tonight is 20%. We should interpret this to mean that 20% of the listeners will have snow in their area tonight. you will not have any snow tonight because the chance of snow is less than 50%. according to historical records when meteorological conditions were the same as today, it snowed twenty percent of the time. it will snow if you are unlucky (or lucky if you like snow) and not snow if you are lucky.

according to historical records when meteorological conditions were the same as today, it snowed twenty percent of the time.

Blocking should be used whenever you want to remove variation associated with the blocking variable from the experimental variation. individuals are grouped before the experiment begins according to some characteristic that is expected to affect the response variable. individuals are similar within the blocks but very different from block to block. all of the above.

all of the above

The sampling distribution of a statistic has the following: shape center spread all of the above

all of the above

Fill in the blank: The sampling distribution of x̅ gives _____ from all possible samples of the same size from the same population. all x̅ values the single value of μ all values of μ all sample values

all x̅ values

When you play solitaire, you either win or lose. Therefore, the probability of winning, according to its definition, is .5 because you either win or lose. approximated by playing lots of times and dividing the number of times you win by the number of times you play. impossible to compute. computed from the number of possible ways the deck of cards can be dealt.

approximated by playing lots of times and dividing the number of times you win by the number of times you play.

Fill in the blank: For the sampling distribution of x̄ created by taking random samples from a left skewed population, the shape is _______________ for large n. slightly skewed right approximately Normal slightly skewed left exactly Normal

approximately Normal

When the data are arranged in ascending numerical order, the median is the value which cuts the data in half. "balances" the data. occurs the most frequently. gives an appropriate measure of the spread of the data.

cuts the data in half.

The larger the sample size, the ________ the degrees of freedom, and the ________ the t distribution is to a normal z distribution. higher, further higher, closer lower, further lower, closer

higher, closer

The test statistic t = x̅-μ/(s/√n) measures the maximum distance between the observed x̄ and the claimed parameter value μ0. how many standard errors the observed x̄ is from the claimed parameter value μ0. the variability of the sample x's about the claimed parameter value μ0. the total number of standard deviations, or σ, unts x is from the claimed parameter value μ0.

how many standard errors the observed x̄ is from the claimed parameter value μ0.

Standard deviation measures where an observation is relative to the other data points. how much the observations in a data set vary about their mean. the change of a variable across time. where the data tend to center..

how much the observations in a data set vary about their mean.

The five number summary for a given data set is [20, 36, 44, 47, 53]. What is the shape of the distribution? symmetric, bell-shaped left-skewed right-skewed uniform

left-skewed

Six balls are in a toy basket. The balls are 1 inch, 2 inches, 3 inches, 3 inches, 4 inches, and 5 inches in diameter. If the 1 inch ball is removed and lost, how will the standard deviation of the diameters of the remaining 5 balls compare with standard deviation of the diameters of the original 6 balls? The standard deviation of the diameters of the remaining 5 balls will be ________ the standard deviation of the original 6 balls. the same as less than greater than

less than

To standardize means to subtract the mean from a given value and then divide by the standard deviation. calibrate the data until they have a normal shape. smooth out irregularities and remove outliers from the data set. center the data set about zero.

subtract the mean from a given value and then divide by the standard deviation.

Which one of the following is the correct representation of the margin of error when sigma is unknown? x̅±t(s/√n) σ/√n z* t (s/√n)

t (s/√n)

Choose the probability that best matches the following statement: "This event is impossible; it cannot occur." 0.0 0.05 0.3 0.6 0.95 1.0

0.0

Suppose the same student took another sample, this time of size 100, and calculated the mean. What is the probability that the sample this student obtained would have a mean of 84 or higher? 0.0003 0.3669 0.6331 0.9997

0.0003

Suppose that the test statistic was -3.00. What is the p-value for this test? p-value < 0.0005 0.0005 < p-value < 0.001 0.001 < p-value < 0.0025 0.002 < p-value < 0.005

0.002 < p-value < 0.005

A manufacturing process produces potato chip bags that have Normally distributed weights, with a mean weight of 15 oz. and a standard deviation of .3 oz. What is the probability that 16 randomly selected bags have a mean weight that exceeds 15.2 oz? 0.9772 0.9962 0.5793 0.5000 0.0038 0.0228

0.0038

What is the probability that a randomly selected adult will have an IQ greater than 140? 0.0038 0.0267 0.6064 0.9962

0.0038

Suppose we were to test the hypotheses H​0 :​ ​μ​ = 80 versus H​a :​ ​μ​ < 80 and computed the standardized value of the test statistic to be t = -2.67 from the sample results of a sample of size n = 22. Using the ​t​ table, what is the ​p​-value? 0.025 < P < 0.05 0.02 < P < 0.025 0.01 < P < 0.02 0.005 < P < 0.01 Cannot find using the t table since the t test statistic value is negative.

0.005 < P < 0.01

Suppose the t test statistic was 2.94. What is the appropriate p-value for this test? 0.001 < p-value < 0.0025 0.002 < p-value < 0.005 0.0025 < p-value < 0.005 0.005 < p-value < 0.01

0.005 < p-value < 0.01

What is the value of the standard error of p̂ for a confidence interval? 0.6 1.56 0.64 0.015

0.015

What proportion of newborn babies weigh more than 10 pounds? 0.9826 0.265 0.0174 0.0179 0.9821

0.0174

What is the probability that a randomly selected adult will have an IQ between 130 and 140? 0.0190 0.4772 0.6700 0.7486

0.0190

Suppose you are testing H​0 :​ ​μ​ = 30 vs. H​a :​ ​μ​ > 30 with a sample of size n = 19 and the test statistic is​ t​ = 1.92. What is the ​p-​value? 0.0192 0.0274 0.025 < p-value < 0.05 0.05 < p-value < 0.10

0.025 < p-value < 0.05

What is the value of the standard error of p-hat? 0.40666 0.2413 0.0008 0.0284

0.0284

Use this information to answer the next three questions. A professor reported that students in a class had scores on the final exam that were left-skewed with a mean of 81.9 and a standard deviation of 6.1. A student took a random sample of 50 students and calculated the mean score to be 80.3. What is the probability that the sample this student obtained would have a mean of 80.3 or lower? 0.0322 0.3974 0.6026 0.9678

0.0322

What is the probability that the mean of n = 75 Pell grant awards will exceed (is greater than) $2700? 0.0173 0.5675 0.9582 0.0418 0.4325

0.0418

What is the standard deviation of the sampling distribution of p̂? 0.00660 0.04737 0.66000 0.00224

0.04737

Choose the probability that best matches the following statement: "This event is very unlikely, but will occur once in a while in a long sequence of trials." 0.0 0.05 0.3 0.6 0.95 1.0

0.05

The average American male has a BMI of 28.6 and having a BMI over 25 is considered obese. In a random sample of 200 men across the US, the sample mean x̄ was found to be a BMI of 26.8. It is known that the population standard deviation σ = 1.7. What is the standard deviation of the sampling distribution of x̄? 24.04 0.12 0.01 15.84

0.12

A couple plans to have three children. There are eight possible arrangements of girls and boys. For example, GGB means that the first two children are girls and the third child is a boy. All eight arrangements are (approximately) equally likely. Write down all eight arrangements of the sexes of three children. Based on the eight arrangements, what is the probability of obtaining any one of these arrangements? 0.0833 0.100 0.125 0.250 0.375 0.500

0.125

What is the area to the left of a z-score of -0.32? 0.3745 0.6255 0.1670 0.2894

0.3745

Let X be the number of girls the couple has. Based on the eight arrangements, what is the probability that X = 2? 0.0833 0.100 0.125 0.250 0.375 0.500

0.375

Use this information to answer the next four questions. To create a 98% confidence interval for the proportion of young adults (ages 18-24) who aren't registered to vote, researchers randomly sample 300 young adults across the United States. Of the 300 sampled, 122 were not registered to vote. What is the value of p-hat? 0.45 0.37 0.39 0.41

0.41

Referring to the above question and assuming that computing the probability is okay, what is the probability that the sample mean is below 35.7? 8786 0.5478 0.4522 0.1214 0.0185

0.5478

Choose the probability that best matches the following statement: "This event will occur slightly more often than not." 0.0 0.01 0.3 0.6 0.99 1.0

0.6

Suppose The Daily Universe wanted to calculate a 95% confidence interval with a margin of error of 0.03. How many BYU returned missionaries need to be randomly sampled? 251 33 34 1068

1068

Referring to question 33, what percentage of IQs are more than 2.5 standard deviations above the mean? 10% 5% 2.5% 0.6% Impossible to determine.

0.6%

What is the probability that any random sample of n = 100 results in an x̅ between 77.3 and 81.1? 0.0796 0.7088 We are unable to compute this probability 0.2027 0.6203

0.6203

The following scenario applies to questions 1-6: The drug Viagra became available in the U.S. in May 1988, in the wake of an advertising campaign that was unprecedented in scope and intensity. A Gallup poll found that by the end of the first week of May, 643 out of 1,005 adults were aware that Viagra was an impotency medication. What is the value of p̂? 0.36 1.56 0.6 0.64

0.64

The time it takes for college freshman to complete the Mason Basic Reasoning Test is normally distributed with a mean of 24 minutes and a standard deviation of 5 minutes. What is the range for the middle 99.7% of the time for the Reasoning Test completion of college freshman? 5 10 15 20 30

30

Corks for bottles in a certain manufacturing process are produced in such a way that the diameter of the corks has a Normal distribution with mean 3 cm. and standard deviation 0.1 cm. The specifications call for corks with diameters between 2.9 and 3.1 cm. What percentage of the produced corks do not meet specifications? 31.74% 53.98% 68.26% 84.13% Cannot be answered with information given.

31.74%

If the researcher wanted to have 95% confidence in the results with a margin of error of 5.1, how many students must be sampled? (Assume σ = 15) 12 34 72 6

34

A couple decides to have two children. Write out each possible combination of boys and girls. For example, the couple could have a boy first and then a girl, which would be written BG. How many distinct combinations are possible? 2 3 4 5

4

Calculate the test statistic for this test. -4.47 0.20 4.47 100

4.47

If you randomly select one student, what is the probability of selecting a freshman or sophomore? 3/6 = 1/2 1/6 2/6 = 1/3 4/6 = 2/3

4/6 = 2/3

How many standard deviations above and below the mean do the quartiles of any Normal distribution lie? (Find the z-scores for Q1 and Q3) 0.25 0.33 0.50 0.67 0.75

0.67

Using the Standard Normal Table, what is the z-score with 0.25 to its right? -0.67 0.67 0.75 -0.75

0.67

What is the probability of getting a sample proportion, p̂, from an SRS of 100 Utah voters between 0.6 and 0.7? 0.0985 0.6975 0.7995 0.1020

0.6975

What is the appropriate t-test statistic for this test? 0.09 0.15 0.99 3.45 6.67

0.99

The following scenario applies to the following three questions: Suppose we have a normal population distribution where μ = 80 and σ = 20. For random samples of size n = 100, what is the probability of getting an x̅ greater than 75? We are unable to compute this probability 0.4013 0.9938 0.0062 0.5987

0.9938

Probability is a measure of how likely an event is to occur. Which of the following is the correct probability of an event that is certain and will occur every time? 0.0 0.3 0.5 0.7 1.0

1.0

Referring to the sampling distribution of x̅ described in the previous question, what is the standard deviation of the sampling distribution of x̅ ? 5.5 4.0 1.0 0.25 0.0625 Cannot be determined

1.0

Use this information to answer the next two questions. The weights of Cougar Tail donuts are known to have a normal distribution with a mean of 5.78 oz and a standard deviation of 0.21 oz. How many standard deviations away from the mean is a donut that weighs 6 oz? 0.22 0.8531 1.05 1.76

1.05

Based on sample results, a 90% confidence interval for the mean servings of fruit per day consumed by grade school children is (0.21, 2.45). What is the margin of error? 2.24 2.01 1.12 0.76

1.12

Ezra's friend, Gwen, takes the math portion of the ACT and scores 27. ACT math scores are Normally distributed with a mean of 20.7 and a standard deviation of 5.0. What is the z-score for Gwen's ACT score? 1.42 2.11 2.03 1.26

1.26

A cork produced by the process described in question 36 has a diameter of 3.135 cm. How many standard deviations is that diameter above the mean? 1.35 .9115 12 5

1.35

Dylan is 73 inches tall. What is his z-score? 1.35 2.60 2.72

1.35

Ezra scores 680 on the mathematics portion of the SAT. The distribution of SAT math scores in recent years has been Normal with a mean of 518 and a standard deviation of 114. What is the z-score for Ezra's SAT math score? 1.93 1.2 2.00 1.42

1.42

Using the Standard Normal Table, what is the z-score with an area of 0.9345 to its left? 0.8289 0.9345 1.51 2.00

1.51

Weights of newborn babies are normally distributed with mean 7.47 pounds and standard deviation 1.2 pounds. How many standard deviations away from the mean is a newborn weighing 9.34 pounds? 1.56 below the mean 2.34 above the mean 0.72 below the mean 1.56 above the mean

1.56 above the mean

What is the value of the t test statistic for this test? 0.58 2.44 1.65 1.55

1.65

Using the Standard Normal Table, what is the z-score with 0.9671 to its left? -0.78 -1.84 1.98 1.84

1.84

What is the test statistic for testing the hypotheses H0: μ =40 vs. Ha: μ > 40? 0.82 1.06 1.21 1.98

1.98

Suppose there are three freshman, one sophomore, and two juniors in a study group. If you randomly select one student, what is the probability of selecting a sophomore? 3/6 = 1/2 1/6 2/6 = 1/3 4/6 = 2/3

1/6

Use this scenario to answer the next three questions. Suppose that a candy company makes a candy bar whose weight is supposed to be 50 grams, but in fact, the weight varies from bar to bar according to a Normal distribution with mean μ = 50 grams and standard deviation σ = 2 grams. The candy company sells bars in packs of 4 (n=4). Construct a control chart for this process. What is the center line of the control chart for this process? 2 100 50 25

50

What percentage of the diameters given in the histogram above lies between Q1 and Q3? 25% 33% 50% 67% 75%

50%

The five-number summary for the length of duration in minutes of Old Faithful's eruptions is [1.7, 2.3, 4.0, 4.4, 5.2]. (Note: These are not the data.) Approximately what percentage of the eruptions last longer than 2.3 minutes? 75% 50% 100% 0% 5% 25% 95%

75%

The mean score of the fourth exam in a statistics class with 1800 students at a large university was 79 with a standard deviation of 14. Suppose twenty-five students are to be randomly selected and their sample mean computed. What will be the mean and standard deviation of the sampling distribution of x̄? 3.16, 0.56 15.8, 0.56 15.8, 2.8 79.0, 14 79.0, 2.8

79.0, 2.8

Can we compute the probability that x̄ is less than 32 for a random sample of size 15? Yes, because we know the mean and standard deviation of the sampling distribution of x̄. Yes, because the sampling distribution of x̄ is Normally distributed. No, because the population is not Normally distributed and we cannot apply the Central Limit Theorem.

No, because the population is not Normally distributed and we cannot apply the Central Limit Theorem.

For random samples of size n = 100, what is the shape of the sampling distribution of x̅? Left skewed Approximately Normal Right Skewed

Approximately Normal

Which one of these random variables is discrete? Height of an adult male GPA Number of phone calls received in a day

Number of phone calls received in a day

For questions 55-59, refer to the following: The article "Action of drugs on movements of rats during swimming" (J. of Human Movement Studies (1984): 225-30) described the effects of the drug ephedrine. Twenty rats were placed in a swimming apparatus where swimming movement triggered rotation of an exercise wheel. The number of revolutions during a fixed time interval was recorded before and after administration of a dose of 5 mg of ephedrine per kilogram of body weight. The response variable is Body weight in kilograms. Dosage in milligrams of ephedrine. Number of revolutions of the exercise wheel. Effect of ephedrine on the rate. Species of rat. Treatment of ephedrine versus no ephedrine.

Number of revolutions of the exercise wheel.

Suppose we are testing the hypotheses H0 : μ = 850 versus the hypothesis Ha : μ >850. For α = 0.05 and p-value = .092, what decision should be made? Reject H0 Fail to reject H0 Reject Ha Fail to reject Ha Accept H0

Fail to reject H0

For a random sample of size 19, can we compute the probability that x̅ is less than 200? Yes, because we know the mean and standard deviation of the sampling distribution of x̅ Yes, because the sampling distribution of x̅ is Normally distributed No, because the population is not Normally distributed and we cannot apply the Central Limit Theorem

No, because the population is not Normally distributed and we cannot apply the Central Limit Theorem

When data are arranged in ascending numerical order, the mean is the value which gives a measure of the consistency of the data cuts the data in half balances the data occurs most frequently

balances the data

Twelve locations were selected in a county where a steel plant is accused of air pollution. At each location, the sulfate level and distance from the steel plant were measured. The data were analyzed to see whether the sulfate level decreases as distance from the plant increases. What type of study is this? Matched pairs experiment Randomized controlled experiment Observational study A double blind experiment Multistage study

Observational study

Which hypothesis is assumed to be true until evidence is found to disprove or contradict it? The null hypothesis. The alternative hypothesis. The claimed hypothesis. The significant hypothesis.

The null hypothesis.

In practice, if we don't know whether the population is normal and our sample size is less than 30, when can we proceed with inference for confidence intervals and hypothesis testing? When the sample standard deviation is not large When the number of successes exceeds the number of failures When α is set very low When the data is single-peaked and there are no outliers

When the data is single-peaked and there are no outliers

A control group where a placebo is administered to each individual allows the researcher to determine The amount of bias in the experimental results. Whether the treatment really worked or whether the subjects responded to a placebo effect. How to match the individuals in the treatment group with the individuals in the control group. The effects of the lurking variable on the response variable.

Whether the treatment really worked or whether the subjects responded to a placebo effect.

When we decrease our sample size and maintain our level of confidence, our margin of error becomes Wider Narrower

Wider

Consider the following metabolic rates: 1772 1666 1362 1460 1867 1439 1614 Suppose the first number in the data set was 1972 instead of 1772. How would this change the value of the median? Increase median Would not change the median Decrease median

Would not change the median

Suppose you have played a game many, many times—winning sometimes and losing sometimes. Can you use the results of playing the game to estimate your overall probability of winning the game?

Yes

In 1990, the average cost of a normal pregnancy and delivery was $4334. Data was collected recently on a random sample of 39 recent births in a particular state. A 90% confidence interval was computed to be ($4663, $4787). On the basis of this interval, can we say that the average cost in that particular state is different from the average cost of $4334? Why or why not? Yes, because $4,334 is outside the confidence interval. Yes, because the mean for the sample of 39 births is $4,725 and that is larger than $4,334. No, because $4,334 is a possible value for the parameter when the sample mean is $4,725. No, because a sample of 39 is not a large enough sample from which we can draw inferences.

Yes, because $4,334 is outside the confidence interval.

Is the sample size large enough to compute a confidence interval for the proportion of adults who were aware that Viagra was an impotency medication after the first week of May? Yes, because more than 10 adults were aware of Viagra Yes, because more than 10 adults were not aware of Viagra Yes, because the sample size is greater than 30 Yes, because both np̂ and n(1-p̂) are greater than 10

Yes, because both np̂ and n(1-p̂) are greater than 10

Fill in the blank: For the sampling distribution of x̄ created by taking random samples from a left skewed population, the standard deviation of the sampling distribution of x̄ ____________ as n increases. decreases stays the same increases cannot be determined

decreases

For the theoretical sampling distribution of x̅ created by taking all possible samples of size 16 from a very left skewed population with μ = 22 and ​σ = 4, the mean of this sampling distribution is approximately equal to 22. is slightly less than 22. is exactly equal to 22. is slightly greater than 22. would approach 22 if the sample size were to continually increase.

is exactly equal to 22.

The standard deviation of the sampling distribution of x̄ is _____________ the standard deviation of the population from which samples of size n >1 are taken to create the sampling distribution. less than equal to greater than not comparable with

less than

For a 95% confidence interval, we are 95% confident that our estimate will not depart from the true population parameter by more than the sample size standard deviation margin of error z* value

margin of error

The null hypothesis is a statement of the many possible values of the statistic. how well the statistic estimates the parameter to be tested. no effect or no change in the population parameter. an estimate of a population parameter.

no effect or no change in the population parameter.

What does significant in the statistical sense mean? no difference of great importance that the test statistic supports the null hypothesis not likely to happen just by chance if H​0 were true

not likely to happen just by chance if H​0 were true

Fill in the blanks: The sample proportion, ____, is used to estimate the population proportion, ____. p ^, p x ¯, μ p, p ^ s, σ

p ^, p

What do we obtain from the sampling distribution of x̄, created assuming the null hypothesis is true, in order to perform a test of hypothesis? Sample size Level of significance or α p-value The value of x-bar

p-value

Which of the following describes confounding? A condition where the effect of one variable on the response variable changes depending on the level of another variable. A condition where the effect of one variable on the response variable cannot be separated from the effect of another variable. A condition where the effect of one treatment on the response variable is different from the effect of another treatment on the response variable.

A condition where the effect of one variable on the response variable cannot be separated from the effect of another variable.

A shoe manufacturer wanted to determine which type of material, "Material X" or "Material Y", to use on the soles of their shoes to get maximum wear. Twenty teenage boys wore one shoe with each type of sole. For each young man, a coin was tossed; if heads, "Material X" would go on the right shoe and "Material Y" on the left. If tails, "Material X" would go on the left shoe and "Material Y" on the right. After wearing these shoes for four months, the thickness of the sole of each shoe was measured. What type of study is this? A randomized controlled experiment. A simple random sample. A voluntary response sample. A matched pairs experiment.

A matched pairs experiment.

A sample of 12th grade students who took the National Assessment of Education Progress year 2000 mathematics test had a mean score of 250. What is the population? All 12th graders All 12th grade students who took the National Assessment of Educational Progress year 2000 mathematics test The mean score for all 12th grade students who took the National Assessment of Educational Progress year 2000 mathematics test 12th grade students who took the National Assessment of Educational Progress year 2000 mathematics test who received a score 250

All 12th grade students who took the National Assessment of Educational Progress year 2000 mathematics test

Researchers for the National Institute of Child Health and Human Development studied 208 infants whose brains were temporarily deprived of oxygen as a result of complications at birth. These babies were subjects in an experiment to determine if reducing body temperature for three days after birth improved their chances of surviving without brain damage. What is the population? All babies who were temporarily deprived of oxygen as a result of complications at birth All babies who have a reduced body temperature for three days after birth The 208 babies who were a part of this experiment All babies who have complications at birth

All babies who were temporarily deprived of oxygen as a result of complications at birth

Why do we sample? A census may be too expensive A census may be time consuming A census may be impractical All of the above

All of the above

Referring to the study on children's caffeine consumption, what is a potential lurking variable? Sugar content: Children may consume caffeinated beverages that also contain sugar, which could affect their sleep patterns. Time of day: Caffeine consumed in the morning may have less effect on sleep patterns than caffeine consumed at night. Age: Older children may be less affected by caffeine than younger children. All of these are potential lurking variables.

All of these are potential lurking variables.

What type of variable is "whether a driver entered the intersection when the light was red at his/her last stop light"? Categorical Quantitative

Categorical

In context, which of the following would be an example of confounding? Confounding caused by the person to person differences in how people react to caffeine and previous caffeine tolerance Confounding in the two groups caused because the volunteers were not randomly sampled There is no reasonable confounding in this study

Confounding caused by the person to person differences in how people react to caffeine and previous caffeine tolerance

A study was performed in order to find out if having your cellphone out, even if you never check it, affects productivity. 250 BYU students in the finance program volunteered for the study, which lasted the course of one semester. All the students were taking the same classes and the students were randomly assigned to either have their phone out for the first half of the semester or the second half. Fifty students were in the "phone out second half" group and 200 students were in the "phone out for first half" group. The average amount of time it took to finish their homework was recorded. Which of the following makes this a poor experiment? Possible confounding because the students were all taking the same classes There wasn't replication because there were only 20 out of the 250 students in the second half group There's no placebo so they would need a "doesn't own a phone" group Confounding due to course difficulty generally increasing as the semester goes on

Confounding due to course difficulty generally increasing as the semester goes on

A librarian is interested in how many books an average visitor checks out. She keeps a tally of how many books are checked out by each visitor as she scans them. What type of sample is this? Simple random sample Convenience sample Multistage sample Stratified sample

Convenience sample

Is the right hand generally stronger than the left in right-handed people? You can crudely measure hand strength by placing a bathroom scale on a shelf with the end protruding, then squeezing the scale between the thumb below and the four fingers above it. The reading of the scale shows the force exerted. Which of the following best describes the design of a matched pairs experiment to compare the strength of the right and left hands using 10 right-handed people as subjects? Each subject squeezes the scale twice: once with his right hand and once with his left hand with the order randomly determined. Scale readings are then compared. Each of the ten right-handed people squeeze the scale. Their scale readings are compared with the scale readings of each of the ten left-handed people. Five of the right-handed people squeeze the scale with their right hand, and the other five with their left hand. Scale readings are then compared. Each subject squeezes the scale first with his right hand and then second with his left hand. Scale readings are then compared.

Each subject squeezes the scale twice: once with his right hand and once with his left hand with the order randomly determined. Scale readings are then compared.

A study of computer-assisted learning examined the learning of "Blissymbols" by children. Blissymbols are pictographs (think of Egyptian hieroglyphs) that are sometimes used to help learning-impaired children communicate. The researcher designed two computer lessons that taught the same content using the same examples. One lesson required the children to interact with the material, while in the other the children controlled only the pace of the lesson. Call these two styles "Active" and "Passive", respectively. Children were assigned at random to Active and Passive groups. After the lesson, the computer presented a quiz that asked the children to identify 56 Blissymbols. What type of study is this? Observational Study Experiment Neither observational study nor experiment

Experiment

Because more questions about statistics have been added to the state exam, a school district decided to add a probability-statistics unit to their ninth-grade general mathematics course. To determine whether the unit will have an impact on scores on the state exam, all ninth-grade students enrolled in a general mathematics course in the largest high school in the new school district were randomly allocated into two groups. One group of 281 students received instruction in a new probability and statistics unit in addition to the traditional instruction; the other group of 311 students received only traditional instruction. Students in both groups were given the state exam at the end of ninth grade to determine whether the group receiving additional instruction in probability and statistics had a higher average score than the group receiving just traditional instruction. Is this study an observational study or an experiment? Observational Study Experiment

Experiment

Two hundred twenty-eight children in a study were assigned to one of three groups. Group one was required to consume 5 mg of caffeine or less each day, Group two was required to consume 5-20 mg of caffeine a day, and Group three was required to consume more than 20 mg of caffeine per day. At the end of three weeks, their parents reported the average amount of sleep their child got each night. What type of study is this? Observational study Experiment

Experiment

R.A. Fisher, a famous statistician, describes a well-known design in his book, Design of Experiments. Five varieties of wheat were compared to determine which gave the highest yield in bushels per acre. Eight farms were available for planting. Each farm was divided into five plots. For each farm, the five varieties were randomly assigned to the five plots with one variety per plot. The varieties were planted on their assigned plots and their yields were measured and compared. What type of study is this? Observational study - multistage sample Experiment - randomized block design Experiment - randomized controlled experiment Observational study - simple random sample Observational study - stratified sample

Experiment - randomized block design

An experiment must have a placebo group in order to be valid.

False

Convenience sampling is a type of probability sampling design.

False

In an experiment, subjects choose their treatment.

False

Probability is the process of drawing conclusions about the sample based on population data.

False

Taking a valid simple random sample eliminates all biases, including bias caused by wording a question in a leading way or using an interviewer who implied that a particular response is desired.

False

The field of statistics ends once we have collected all of our data.

False

The term "population" can only be applied to people.

False

We can establish causation whenever a random sample is taken.

False

To determine whether there is a relationship between amount of time spent commuting to work each day and overall job satisfaction, a researcher surveyed 100 people that commute to work and asked them to report the average number of minutes they spent commuting to and from work each day during the previous week and rate their job satisfaction on a scale from 1 to 10. What is the response variable in this example? Amount of time spent commuting to work each day Overall job satisfaction

Overall job satisfaction

In context, what is the subject in the experiment? Individual volunteers Individual groups (caffeine and no caffeine) The score received

Individual volunteers

What is the final step in the Big Picture of Statistics? Exploratory data analysis Inference Produce data Probability

Inference

What does the statistical term "population" refer to? It always refers to the United States population It refers to the group we want to study or learn something about It refers to the subset of the group we want to study It refers to a set of principles that guide the study of statistics

It refers to the group we want to study or learn something about

Gas mileage was compared for Premium and Regular gas for twenty Toyota Prius cars. Each car was run on a tank of Premium gas and on a tank of Regular gas. Before the study, a coin was tossed for each car. If the coin was heads, the car was first tested with Premium gas; if the coin was tails, the car was first tested with Regular gas. At the end of the study, average miles per gallon for the two types of gas was compared. What type of study is this? Observational Study Randomized Controlled Experiment Matched Pairs Experiment Randomized Block Experiment

Matched Pairs Experiment

What is the explanatory variable? Pain score Band-aid size Which band-aid was removed first Method of band-aid removal

Method of band-aid removal

A large university in the western United States wants to survey the faculty regarding its plan to combine the spring and summer terms into one semester. It randomly selects 5 colleges on its campus and from each of these colleges, randomly selects 4 departments. Within the chosen departments, 4 faculty members are selected to be included in the sample. What type of sampling design is this? Simple random sample Stratified sample Multistage sample Convenience sample

Multistage sample

Medical experiments are often double blind in nature. What does this mean? The subjects in the control group receive a placebo treatment Neither the subject nor the person evaluating the subject (the doctor or nurse) knows which treatment the subject receives All data on individuals are kept confidential Subjects are randomly assigned to treatments without the doctor's knowing how the randomizing was done

Neither the subject nor the person evaluating the subject (the doctor or nurse) knows which treatment the subject receives

Who are the subjects in this study? The classrooms receiving the traditional instruction The classrooms receiving the new instruction Ninth-grade students enrolled in a general mathematics course All high school students

Ninth-grade students enrolled in a general mathematics course

Which one of the following is not a consequence of lack of randomization? Results could be biased. The sample will not be representative of the population. Laws of probability cannot be used to measure uncertainty in conclusions. Not enough individuals will be available to measure chance variation.

Not enough individuals will be available to measure chance variation.

Researchers want to determine if there is a link between whether an individual uses illegal drugs and whether they graduated from high school. They randomly survey 300 people and asked them these questions: "Did you graduate from high school?" "Have you ever used illegal drugs?" What type of study is this? Observational Study Randomized Controlled Experiment Matched Pairs Experiment Randomized Block Experiment

Observational Study

To investigate the effects of the drug phen-fen, 200 women in the 30-40 age range who had used the drug for at least one year were located. 200 women of the same age group who had not used the drug were also located. The incidence of heart valve abnormality was compared between the two groups. What type of study is this? Observational Study Randomized Controlled Experiment Randomized Block Experiment Matched Pairs Experiment

Observational Study

Two hundred twenty-eight surveyed parents reported the amount of caffeine their 8 to 12 year old children consumed on a typical day. They also gave the average time their children slept each night. The purpose of the study was to determine whether amount of caffeine consumed affected how much children 8 to 12 years old sleep. What type of study is this? Observational study Experiment

Observational study

Which of the following is not part of the Big Picture of Statistics? Collecting data Summarizing data Interpreting data Publishing data

Publishing data

In a telephone survey, drivers were asked, "Recalling the last ten traffic lights you drove through, how many were red when you entered the intersection?" What type of variable is "number of traffic lights that were red"? Categorical Quantitative

Quantitative

Consider the following two survey questions: Question 1: How satisfied are you with your current job: very satisfied, somewhat satisfied, somewhat dissatisfied, very dissatisfied? Question 2: What do you think can be improved about your job? Which of the following statements is true? Question 1 is an open question and Question 2 is a closed question Question 1 is a closed question and Question 2 is an open question Both are open questions Both are closed questions

Question 1 is a closed question and Question 2 is an open question

Consider these two survey questions:How often do you read a book for fun (outside of work or school)?How often do you read a book for fun (outside of work or school): never, sometimes, or often? Are these examples of open or closed questions? Question 1 is an open question and Question 2 is a closed question. Question 1 is a closed question and Question 2 is an open question. Both are examples of closed questions. Both are examples of open questions.

Question 1 is an open question and Question 2 is a closed question.

When people were asked whether they would "favor or oppose taking military action in Iraq to end Saddam Hussein's rule," 68% said they favored military action while 25% said they opposed military action. However, when asked whether they would "favor or oppose taking military action in Iraq to end Saddam Hussein's rule even if it meant that U.S. forces might suffer thousands of casualties," responses were dramatically different; only 43% said they favored military action while 48% said they opposed it. What type of bias is this? Undercoverage bias Non-response bias Response Bias Question wording bias

Question wording bias

Which of the following is a false statement about statistics? Collecting data from the entire "population" may be impossible. Statistical information is never misleading or misrepresented. All statistical summaries and conclusions should be reported in context. Publishing research results is not a part of the Big Picture of Statistics.

Statistical information is never misleading or misrepresented.

The college of humanities in a large university was accused of discrimination in their faculty hiring. Twenty records of the recent female applicants who were not hired and twenty records of recent male applicants who were not hired were randomly selected and compared with the records of the recent hires. What type of sampling design is this? Simple random sample Stratified sample Convenience sample Multistage sample

Stratified sample

Researchers for the National Institute of Child Health and Human Development studied 208 infants whose brains were temporarily deprived of oxygen as a result of complications at birth. These babies were subjects in an experiment to determine if reducing body temperature for three days after birth improved their chances of surviving without brain damage. What is the sample? All babies who were temporarily deprived of oxygen as a result of complications at birth All babies who have a reduced body temperature for three days after birth The 208 babies who were apart of this experiment All babies who have complications at birth

The 208 babies who were apart of this experiment

Four of the following express potential problems to the Band-aid study, but one is not a potential problem. Which one of the following is not a potential problem? Amount of hair on the subject's arm may affect degree of pain Results may be biased because there is not blinding of subjects as to when they receive which treatment. The study was not double blind. In fact, it was not even single blind. Subjects may already prefer one method of removal over another, so results may be biased. The study lacks realism because the subjects can't tell how each Band-aid is removed.

The study lacks realism because the subjects can't tell how each Band-aid is removed.

What is the explanatory variable in this study? The exam taken at the end of the year The high school a student attended The type of general mathematics instruction received; new instruction or traditional instruction The new instruction

The type of general mathematics instruction received; new instruction or traditional instruction

A randomized block design should be used when the subjects within groups (called blocks) are similar in ways that affect the response variable, but different from one block to the next.

True

An experiment that doesn't incorporate randomization is NOT a valid experiment.

True

In a random digit telephone survey, homeless people or people with only cell phones do not have telephones that can be called with random digit dialing. What type of bias is this? Non-response bias Undercoverage bias Response bias due to respondent lying or deliberately giving incorrect information Response bias due to question wording Response bias due to interviewer influences

Undercoverage bias

An experiment was designed using school children as subjects to determine whether milk prevented their catching colds. The researcher randomly assigned 100 school children to two groups: one group of 50 to receive a cup of milk at school each day and the other group of 50 to receive no milk at school. What is the response variable? Remember: The response variable is measured on the individual. Whether the child received a cup of milk at school each day Whether the child caught a cold The number of children who received a cup of milk at school each day The number of children who caught a cold

Whether the child caught a cold

In the milk study, what is the explanatory variable? Whether the child received a cup of milk at school each day Whether the child caught a cold The number of children who received a cup of milk at school each day The number of children who caught colds

Whether the child received a cup of milk at school each day

An experiment was designed using school children as subjects to determine whether drinking milk prevented their catching colds. The researcher randomly assigned 100 school children to the two groups: one group of 50 to receive a cup of milk at school each day and the other group of 50 to receive no milk at school. What is a potential lurking variable? Whether the child drank milk at school Whether the child caught a cold Whether the child was frail or robust at the beginning of the experiment Whether the child was a good student or a poor student

Whether the child was frail or robust at the beginning of the experiment

Is this study described above a valid experiment? No, there was no control or comparison group. No, randomization was not met. No, there was no replication in this study. No, this is an observational study. Yes, all of the principles for a valid experiment are met.

Yes, all of the principles for a valid experiment are met.

Referring to the previous question, was replication incorporated? Yes, because each treatment group had 20 subjects. Yes, because the experiment was repeated on another set of boys. No, because the experiment was not repeated on another set of boys. No, because there was more than one subject in the experiment.

Yes, because each treatment group had 20 subjects.

Was using the eight farms as blocks appropriate? Yes, because each farm was large. Yes, because it removes lurking variables from farm to farm. No, because each fertilizer should be a block.

Yes, because it removes lurking variables from farm to farm.

An experiment was designed using school children to determine whether drinking milk prevented their catching colds. The researcher randomly assigned 100 school children to two groups—one group of 50 to receive a cup of milk at school each day and the other group of 50 to receive no milk at school. Does the study incorporate control/comparison? Yes, because the "No milk" group was compared to the "Received milk" group. No, because there was only one treatment of "receive one glass of milk each day" in the study.

Yes, because the "No milk" group was compared to the "Received milk" group.

Does the study described incorporate the principle of replication? Yes, because there were 281 students in one group and 311 in the other group (more than one individual per treatment group) No, because the study was no repeated another year (the experiment only happened once)

Yes, because there were 281 students in one group and 311 in the other group (more than one individual per treatment group)

Does this study described incorporate the principle of randomization? Yes, because we are told that "students ... were randomly allocated ..." No, because students registered for whichever section they wanted

Yes, because we are told that "students ... were randomly allocated ..."

Does the study incorporate randomization? Yes, subjects were randomly sampled. No, subjects were not randomly sampled. Yes, both the order in which the band-aids were removed and which band-aid was removed with which treatment were randomized.

Yes, both the order in which the band-aids were removed and which band-aid was removed with which treatment were randomized.

Does the study incorporate replication? No, since they only did the experiment once. Yes, since there were 50 children in each treatment group. Yes, since there were 100 children total that were tested

Yes, since there were 50 children in each treatment group.

Which of the following is a categorical variable? Height Zip code Mile time Book costs

Zip code

A reporter for the university newspaper wants to find out the opinions that all BYU students have about the university health center. During a class break, he goes to the health center, contacts a few students as they exit, and asks them to fill out a survey. What type of sample is this? a simple random sample a stratified sample a multistage sample a convenience sample

a convenience sample

Which of the following is not a valid probability sample? a simple random sample a stratified sample a multistage sample a convenience sample

a convenience sample

Educators in California are concerned about a recent newspaper article reporting that students in the United States are falling behind students in other nations in their math skills. They decide to sample 10th grade students throughout the state and test their mathematics skills. They first randomly select 10 school districts. From each of these 10 school districts they randomly select three high schools. From these 3 high schools they randomly select 10 students and test them. What type of sample is this? a simple random sample a stratified sample a multistage sample a convenience sample

a multistage sample

A popular magazine is interested in the average amount of time that their readers spend on the internet each day. They randomly survey 100 of their female readers and 100 of their male readers and ask them about their average internet use. What type of sample is this? a convenience sample a volunteer sample a stratified sample a cluster sample

a stratified sample

A high school teacher wants more information about her students' study habits. She writes each of her students' names on an identical slip of paper and places them in a hat. After mixing up the papers, she selects 30 students from the hat. She then asks the question, "How many hours a week do you study outside of school, 0-3, 4-6, or more than six?" and records their responses. What type of sample is this? simple random sample stratified sample multistage sample cluster sample

simple random sample

The nonprofit group Public Agenda conducted telephone interviews with parents of high school children. Interviewers chose equal numbers of black, white, and Hispanic parents by randomly selecting from within each race using student records. One question asked was "Are the high schools in your state doing an excellent, good, fair, or poor job, or do you not know enough to say?" What type of sample is this? convenience sample simple random sample stratified sample multistage sample

stratified sample

In the scenario, what is the sample? a subset of students currently enrolled in STAT121 the 200 students interviewed all students who took STAT121 last semester all BYU students

the 200 students interviewed

In the scenario, what is the sample? all beaches in California all swimming beaches in California the 45 beaches that were sampled all beaches that fail the water quality test

the 45 beaches that were sampled

Using the information from questions 1-3, suppose that p̂ is 0.40 and the standard error of p̂ is 0.10. Compute a 90% confidence interval for the proportion of adults that were aware of Viagra. (0.2355, 0.4) (0.3, 0.5) (0.2355, 0.5645) (0.2355, 0.4)

(0.2355, 0.5645)

Suppose we have H​0 :​ μ = 30 versus H​a :​ μ > 30 with p-value = .032. If we decided to test H​0 :​ μ = 30 versus H​a:​ μ ​≠ 30, what is the ​p-value for this new H​a​ assuming all other factors are the same? .016 .032 .050 .064

.064

Statistical inference can be defined as making generalizations about the population based on sample data.

True

Use this information to answer the next six questions. The Federal Pell Grant Program provides need-based grants to low-income undergraduate and certain postbaccalaureate students to promote access to postsecondary education. According to the National Postsecondary Student Aid Study conducted by the U.S. Department of Education in 2008, the average Pell grant award for 2007-2008 was $2,600. Assume that the standard deviation, σ, in Pell grant awards was $500. Suppose we take random samples of size 75. What will the mean of the sampling distribution of x̄ be? $500 $300.23 $2,600 $5,200

$2,600

For samples of size 75, what will the standard deviation of the sampling distribution of x̄ be? $57.74 $27.21 $6.67 $500

$57.74

Pew Research reported a margin of error of 2.5% for 98% confidence. What is the 98% confidence interval for the proportion of adults ages 18-34 who are dissatisfied with their job? (0.4882, 0.5382) (0.4632, 0.5632) (0.4923, 0.5221) (0.4797, 0.5568)

(0.4882, 0.5382)

The following scenario applies to the next three questions: The IQ level of students at a particular university has an unknown mean. A simple random sample of 100 students is found to have a sample mean IQ of x̅ = 115 and a sample standard deviation of s = 15. Calculate a 95% confidence interval for the mean IQ level of all students in the university. (113, 117) (100, 130) (112, 118) (114.7, 115.3)

(112, 118)

Calculate a 95% confidence interval for the mean number of calories for all large orders of fries. (548.37, 571.63) (528.37, 551.63) (553.16, 574.84) (529.16, 550.84)

(548.37, 571.63)

The following scenario applies to questions 7-8: The Intel Corporation is conducting quality control on its circuit boards. Thickness of the manufactured circuit boards varies unavoidably from board to board. Suppose the thickness of the boards produced by a certain factory process varies normally. The distribution of thickness of the circuit boards is supposed to have the mean μ = 12 mm if the manufacturing process is working correctly. A random sample of five circuit boards is selected and measured, and the average thickness is found to be 9.13 mm. The standard deviation for the sample is computed to be 1.11 mm. Calculate a 95% confidence interval for the mean thickness of the circuit boards. (8.02, 10.24) (8.63, 9.63) (7.17, 11.09) (7.75, 10.5)

(7.75, 10.5)

The BYU Testing Center is known for being the location with the most prayers said per capita. Researchers asked a random sample of 49 BYU students in winter 2019 to estimate the number of prayers they said in the BYU Testing Center the previous semester. Researchers plan to use these data to estimate the mean number of prayers said by students the previous semester in the BYU Testing Center with 99% confidence. They obtained a sample mean of 10.92 prayers with a standard deviation of 7.53. What is the confidence interval estimate? (10.50, 11.34) (8.04, 13.80) (8.15, 13.69) (10.79, 11.05) (8.01, 13.83)

(8.01, 13.83)

Find a 95% confidence interval for μ when n = 9, x̄ = 103.14 and s = 5.25. (99.10, 107.18) (99.71, 106.57) (101.39, 104.89) (101.79, 104.49)

(99.10, 107.18)

What is the z-score for a baby weighing 4.5 pounds? 2.48 -2.48 -1.45 1.90

-2.48

Suppose the test statistic was 2.67. What is the associated p-value? p-value < .0005 p-value < .001 .0025 < p-value < .005 .025 < p-value < .05

.0025 < p-value < .005

Suppose the test statistic is 1.37. What is the p-value for this one-sided test? .05 < p-value < .10 p-value < .0005 .10 < p-value < .20 .10 < p-value < .05

.05 < p-value < .10

Suppose we take a random sample of size 75. What is the probability that the mean of the 75 awards is less than $2,550? 0.1922 It is not appropriate to calculate probabilities in this situation. 0.1340 0.8660 0.4602

0.1922

The following situation applies to the next four questions: The Weschler Adult Intelligence Scale (WAIS) is the most common "IQ" test. The scale of scores is approximately Normal with a mean of 100 and a standard deviation of 15. What proportion of adults have an IQ less than 90? (Draw and label the Normal curve and use the Standard Normal Table) -0.67 0.2514 0.3707 0.7486

0.2514

Choose the probability that best matches the following statement: "This event is less likely to occur, but it is not extremely unlikely." 0.0 0.05 0.3 0.6 0.95 1.0

0.3

A manufacturing process produces bags of cookies that have Normally distributed weights with a mean of μ = 15.0 oz. and a standard deviation of σ = 0.4 oz. What is the probability that a randomly selected bag weighs more than 15.2 oz? 0.9772 0.6915 0.5793 0.5000 0.3085 0.0228

0.3085

What is the probability that a randomly selected student scored lower than 33 on the ACT? (Hint: consider the 68-95-99.7 rule.) 0.025 0.840 0.975 0.9985

0.975

What is the numerical value of the statistic p̂ that estimates p? 0.107 1.187 0.127 0.843

0.843

Choose the probability that best matches the following statement: "This event is extremely likely, but occasionally it will not occur in a long sequence of trials." 0.00 0.05 0.30 0.60 0.90 1.00

0.90

Using the Standard Normal Table, what proportion of observations on the Standard Normal Curve satisfy -1.65 < z < 1.75? 0.0022 0.0463 0.0495 0.9104 0.9599 0.9978

0.9104

What proportion of newborn babies weigh between 4.5 and 9.5 pounds? 0.6597 0.7823 0.9833 0.9479

0.9479

Use this information to answer the next three questions. Scores on the math portion of the SAT follow a Normal distribution with a mean of 507 and a standard deviation of 111. What is the probability that any random sample of 4 students has an average SAT math score between 400 and 625? 0.0166 0.0268 0.9566 0.9834

0.9566

Above what value are 20% of all IQ scores? 0.7881 85.0 87.4 112.6 115.0

112.6

What is the lower limit of the control chart for this process? 14.8 14.4 14.0 14.6 14.2

14.4

Referring to the manufacturing process in question 12 above, what are the lower and upper limits for the control chart for x̅ from samples of size 16? 13.8, 16.2 14.9, 15.1 14.8, 15.2 11.4, 18.6

14.8, 15.2

In order to construct an x̄-chart for this process, what number should be used as the center line? 15.4 15.0 14.6 14.8 15.2

15.0

What is the upper limit of the control chart for this process? 15.4 15.6 16.2 15.8 15.2

15.6

Use this information to answer the next two questions. A biologist wishes to estimate the mean number of teeth in an adult tiger shark. He wishes to generate a 99% confidence interval with a margin of error of 4 teeth. The standard deviation, σ, is known to be 21.3. How many tiger sharks much he sample? 13 14 76 189

189

The manager of a major chain department store decided to offer a promotion to increase customers' usage of their credit cards issued by the chain. Before the promotion, credit card holders used their cards an average of 6.3 times per month. During the month of the promotion a random sample of 100 credit card holders used their cards an average of 6.8 times with a standard deviation of 2.5. For testing the hypotheses H​0 :​ μ = 6.3 versus H​a :​ μ > 6.3, what is the value of the standardized test statistic? 0.20 0.50 2.00 Impossible to determine from information given.

2.00

Scores on a standard IQ test are approximately normally distributed with a mean of 100 and a standard deviation 15. If Joe's score is 133, how many standard deviations is Joe's score above the mean? 33 15 6.6 2.2 1.5

2.2

What is the value of z* for 98% confidence? 1.645 1.96 2.33 2.56

2.33

Calculate the margin of error from a random sample of 27 pigs with a mean weight of 54.3 kg and a standard deviation ​s​ = 6.2 kg. Use 95% confidence. 0.22 kg. 0.45 kg. 1.13 kg. 2.45 kg. 21.48 kg.

2.45 kg.

What is the t* associated with 98% confidence and df = 37? 2.326 2.423 2.457 2.042

2.457

For corks described in question 36, below what diameter are the smallest 10% of the corks? .5398 cm 2.540 cm 2.872 cm 2.999 cm 3.001 cm 3.067 cm

2.872 cm

Below what score do 25% of students fall? (Round your answer to the nearest whole number.) 289 433 507 581

433

What is the lower limit of the control chart for this process? 47 44 48 43

47

A poultry farmer wishes to estimate the average incubation period (the number of days between a hen laying her egg and the time the egg hatches) for eggs on his farm. He plans to take a sample and make a 98% confidence interval, and would like a margin of error of half a day. It is known that the distribution of incubation lengths has a standard deviation of 1.5 days. How many eggs does he need to sample to create the desired interval? 6 17 49 147

49

Suppose that on a farm there are 3 cows, 5 horses, and 10 chickens. If you randomly select one farm animal, what is the probability of selecting a horse? 5/8 3/18 5/18 8/18 10/18

5/18

What is the upper limit of the control chart for this process? 53 56 52 57

53

Heights of males in the United States are normally distributed with a mean of 69.5 inches and a standard deviation of 2.6 inches. Between what two values do the middle 99.7% of all males in the United States fall? 64.3 and 74.7 inches 61.7 and 77.3 inches 59.1 and 79.9 inches

61.7 and 77.3 inches

The height of American men (ages 20-30) is normally distributed with an average of 69.5 inches and a standard deviation of 3 inches. Between what two heights are the middle 95% of American men? 69.5 to 75.5 inches 63.5 to 75.5 inches 66.5 to 72.5 inches 68 to 71 inches

63.5 to 75.5 inches

Use this information to answer the next two questions. An advertiser wishes to estimate the proportion of adults in Utah who already own a gym membership. He wishes to create a 90% confidence interval with a margin of error of 0.10. How many people must he sample? 63 72 67 68

68

What are the appropriate degrees of freedom for this test? 6 8 4 5 7

7

A major US city reported the height, in feet, of the tallest 13 buildings in its metropolitan area. The heights of these buildings were: 868, 734, 709, 650, 631, 834, 902, 679, 855, 650, 635, 789, 668 Make a stem plot of these data by hand. Round the heights to the nearest tens place. Use stems of 6, 7, 8, and 9 with, for example, 868 having a 7 on the 8 row, 650 having a 5 on the 6 row, and 734 having a 3 on the 7 row. What is the best description of your stem plot? What is the best description of the shape of your stemplot? A single peaked, symmetric distribution A bimodal distribution A single peaked, right-skewed distribution A single peaked, left-skewed distribution

A single peaked, right-skewed distribution

Archaeologists plan to examine a sample of two-meter-square plots near an ancient Greek city for artifacts visible in the ground. They randomly choose three plots from each of the following areas: floodplain, coast, foothills, and high hills. What kind of sample is this? A simple random sample A stratified random sample A voluntary response sample A convenience sample

A stratified random sample

Suppose the p-value is 0.135. What is the correct interpretation of this p-value? There is a 0.135 probability that the average time full-time corporate employees work per week is greater than 40. There is a 0.135 chance that the null hypothesis is true. Assuming the null hypothesis is true, there is a 0.135 probability of obtaining a sample statistic as extreme or more extreme than what we calculated. Assuming the alternative hypothesis is true, there is a 0.135 probability of obtaining a sample statistic as extreme or more extreme than what we calculated.

Assuming the null hypothesis is true, there is a 0.135 probability of obtaining a sample statistic as extreme or more extreme than what we calculated.

What would be an example of a Type I error in the context of this problem? Believing that the mean NAEP math score is higher than 275 when it is actually higher Believing that the mean NAEP math score is higher than 275 when it is not actually higher Believing that the mean NAEP math score is not higher than 275 when it is actually higher Believing that the mean NAEP math score is not higher than 275 when it is not actually higher

Believing that the mean NAEP math score is higher than 275 when it is not actually higher

Normal curve G has a mean of 50 and a standard deviation of 5. Normal curve H has a mean of 50 and a standard deviation of 10. How do the shapes of these two Normal curves compare if they are drawn using the same scale? Both are centered at 50, but curve G is taller and skinnier than curve H Both are centered at 50, and both have the same height Both are centered at 50, but curve G is flatter and more spread out than curve H

Both are centered at 50, but curve G is taller and skinnier than curve H

Three children are in a room, ages 3, 4, and 5. A fourth child enters aged 6. What can we say about the mean and standard deviation of the ages? The mean stays the same, but the standard deviation increases. The mean stays the same, but the standard deviation decreases. The mean and standard deviations stay the same. Both the mean and standard deviation increase.

Both the mean and standard deviation increase.

Statistically significant means that there is enough evidence to reject the null hypothesis, whereas practical significance can only be determined by the researcher if the results are worth acting upon.

True

In a study to determine which new flavor of soda to release, the company performed a blind taste test where the participants didn't know which variant of soda was in which cup. The cups were marked 1, 2, and 3 respectively, and the participant was asked to choose which one they liked best. Is the response variable in this experiment quantitative or categorical? Quantitative Categorical

Categorical

Use this information to answer the next three questions. A fast food chain claims that a large order of french fries has 540 calories. To test the claim that the true mean is actually higher, a sample of 15 large orders of french fries is taken. The sample mean is 560 and the sample standard deviation is 21. Since the sample size is small, how could we check the condition of normality for this test? Check if the standard deviation is small. Check a plot of the data for no outliers or skewness. We can't. If the sample size isn't large enough, we can't perform the test. Check if the alpha level is low.

Check a plot of the data for no outliers or skewness.

Which of the following confidence levels and significance levels are appropriate for using a confidence interval approach to hypothesis testing? Confidence Level = 99% and α = 0.01 Confidence Level = 95% and α = 0.01 Confidence Level = 95% and α = 0.5 Confidence Level = 90% and α = 0.01

Confidence Level = 99% and α = 0.01

The advertiser realizes he cannot afford to sample more people, but he would like a smaller margin of error. What must he do to obtain a smaller margin of error with the same sample size? Decrease his confidence level Increase his confidence level

Decrease his confidence level

Suppose the p-value of the test is found to be 0.0715 using statistical software. What is the appropriate conclusion at α = 0.05. Reject the null hypothesis. We have sufficient evidence to conclude that the mean price of a set of tires is significantly greater than $150. Fail to reject the null hypothesis. We have sufficient evidence to conclude that the mean price of a set of tires is significantly greater than $150. Fail to reject the null hypothesis. We do not have sufficient evidence to conclude that the mean price of a set of tires is significantly greater than $150. Reject the null hypothesis. We do not have sufficient evidence to conclude that the mean price of a set of tires is significantly greater than $150.

Fail to reject the null hypothesis. We do not have sufficient evidence to conclude that the mean price of a set of tires is significantly greater than $150.

Suppose the p-value was found to be 0.1629 using statistical software. What is the appropriate conclusion when α = .10? Reject the null hypothesis. We have sufficient evidence to conclude that the true mean number of calories in a hamburger is greater than 310. Reject the null hypothesis. We have insufficient evidence to conclude that the true mean number of calories in a hamburger is greater than 310. Fail to reject the null hypothesis. We have sufficient evidence to conclude that the true mean number of calories in a hamburger is equal to 310. Fail to reject the null hypothesis. We have insufficient evidence to conclude that the true mean number of calories in a hamburger is greater than 310.

Fail to reject the null hypothesis. We have insufficient evidence to conclude that the true mean number of calories in a hamburger is greater than 310.

If there is not enough evidence to support the alternative hypothesis, we can accept the null hypothesis.

False

Increasing the sample size will lead to a wider margin of error.

False

Interval estimation is a form of statistical inference in which we estimate an unknown parameter using a single number that is calculated from the sample data.

False

Observational studies cannot have control groups.

False

The Law of Large Numbers states that as the number of trials increases, the relative frequency of an event gets further and further from the theoretical probability.

False

The mean is a measure of spread.

False

The mean of the theoretical sampling distribution of x̄ gets closer to μ as n increases.

False

The null hypothesis is the claim that the researcher wants to prove.

False

The p-value gives the probability that the null hypothesis is true.

False

The researchers decided that it was too expensive to sample as many as was required for their calculations. To decrease the required sample size and therefore the cost, they could increase their confidence level and decrease the desired margin of error.

False

The shape of the histogram of sample data gets closer to the shape of the Normal distribution as the sample size increases.

False

The shape of the theoretical sampling distribution of x̄ is always Normal.

False

The standard deviation of x̄ (for n > 1) is always less than the standard deviation of the population.

False

The value of a sample statistic usually equals the value of the parameter of the population from which the sample was taken.

False

To be able to safely compute a confidence interval, the only condition that must be met is that the data came from a random sample.

False

True or False: If results are statistically significant, then they are always practically significant.

False

True or False: Important differences are always statistically significant if a large sample size is used.

False

We can never compute probabilities on x̅ when the population is skewed.

False

When outliers are present in our data, the mean is preferred over the median.

False

When sigma is unknown it is impossible to compute a confidence interval for μ

False

When the value of the population standard deviation is unknown, the only change that occurs in the calculation of our confidence interval is we use s rather than σ.

False

Suppose the z-score for Gwen's Math ACT score is 1.2, what is the correct interpretation of this z-score? Gwen's ACT score is 1.2 points above the mean Gwen's ACT score is 1.2 percent above the mean Gwen's ACT score is 1.2 standard deviations above the mean Gwen's mean ACT score is 1.2 standard deviations below the mean

Gwen's ACT score is 1.2 standard deviations above the mean

The following scenario applies to the next four questions: A certain prescription medicine is supposed to contain an average of 250 parts per million (ppm) of a certain chemical. If the concentration is higher than this, the drug may cause harmful side effects; if it is lower, the drug may be ineffective. The manufacturer runs a check to see if the mean concentration in a large shipment conforms to the target level of 250 ppm or not. A simple random sample of 100 portions is tested, and the sample mean concentration is found to be 247 ppm. The sample concentration standard deviation is s = 12 ppm. What are the appropriate null and alternative hypotheses? H 0: x̄ = 250 vs. H a: x̄ < 250 H 0: x̄ = 250 vs. H a: x̄ ≠ 250 H 0: x̄ = 250 vs. H a: x̄ > 250 H 0: μ = 250 vs. H a:μ < 250 H 0: μ = 250 vs. H a: μ ≠ 250 H 0: μ = 250 vs. H a: μ > 250

H 0: μ = 250 vs. H a: μ ≠ 250

What are the null and alternative hypotheses? H 0: μ = 780 vs. H a: μ > 780 H 0: x̄ = 780 vs. H a: x̄ ≠ 780 H 0: μ = 780 vs. H a: μ ≠ 780 H 0: μ = 780 vs. H a:μ < 780

H 0: μ = 780 vs. H a: μ ≠ 780

The mean weight for starting football players on a top 20 team in Division I was 105 kg in the 1988 football season. The question asked by a researcher was whether starters on non-top 20 teams weighed less than 105 kg on the average. Thirty six starting players on non-top 20 teams were randomly selected. What are the null and alternative hypotheses necessary to answer the question, "Is the mean weight for non-top 20 starters less than 105 kg?" H0 : μ = 105 versus Ha : μ <105 H0 : μ = 105 versus Ha : μ >105 H0 : μ = 105 versus Ha : μ ≠105 H0 : x̅ = 105 versus Ha : x̅ <105 H0 : x̅ = 105 versus Ha : x̅ >105 H0 : x̅ = 105 versus Ha : x̅ ≠105

H0 : μ = 105 versus Ha : μ <105

A quality control engineer needs to determine whether the oven temperature for a certain model is properly calibrated on average. Ten ovens are set at 300o​ ​F, and after one hour, the actual temperature will be measured. What hypotheses should be used to test whether the average temperature differs from 300o ​F? H0 : μ = 300 versus Ha : μ >300 H0 : μ = 300 versus Ha : μ <300 H0 : μ = 300 versus Ha : μ ≠300 H0 : x̅ = 300 versus Ha : x̅ >300 H0 : x̅ = 300 versus Ha : x̅ <300 H0 : x̅ = 300 versus Ha : x̅ ≠300

H0 : μ = 300 versus Ha : μ ≠300

The following situation applies to Questions 1-6: A tire store advertises that the average price of a new set of their tires is only $150. One of their recent customers believes their advertised average is too low - that the true mean price for a set of tires exceeds $150. He plans to carry out a hypothesis test at α = 0.05. In order to perform the test, the customer took an SRS of 8 sets of tires recently sold. The mean of these sets of tires was x̅ = $156.90 and the standard deviation was s = $11.80. What are the appropriate null and alternative hypotheses for this test? H0: μ = 150 vs. Ha: μ < 150 H0: μ = 150 vs. Ha: μ > 150 H0: x̅ = 150 vs. Ha: x̅ < 150 H0: x̅ = 150 vs. Ha: x̅ > 150

H0: μ = 150 vs. Ha: μ > 150

Use this information to answer the next five questions. The National Assessment of Educational Progress (NAEP) is administered annually to 4th, 8th, and 12th graders in the United States. On the math assessment, a score above 275 is considered an indication that a student has the skills to balance a checkbook. Believing that the true mean score is much higher, a researcher takes a random sample of 500 young men between the ages of 18 and 20 and calculates the mean NAEP math score to be 280. The standard deviation of math scores for the sample of young men was 25. What are the appropriate null and alternative hypotheses? H0: x̄ = 275 vs. Ha: x̄ < 275 H0: x̄ = 275 vs. Ha: x̄ ≠ 275 H0: x̄ = 275 vs. Ha: x̄ > 275 H0: μ = 275 vs. Ha: μ < 275 H0: μ = 275 vs. Ha: μ ≠ 275 H0: μ = 275 vs. Ha: μ > 275

H0: μ = 275 vs. Ha: μ > 275

Use this information to answer the next 5 questions. A fast food chain claims their regular hamburgers have an average of 310 calories. One consumer believes this average is actually much higher and takes a random sample of 45 hamburgers. The mean of this sample is x ¯ = 314, and standard deviation is s = 27. What are the appropriate hypotheses? H0: x ¯ = 310 vs. Ha: x ¯ >310 H0: μ = 310 vs. Ha: μ >310 H0: x ¯ = 314 vs. Ha: x ¯ >314 H0: μ = 314 vs. Ha: μ >314

H0: μ = 310 vs. Ha: μ >310

What type of graph would be best for displaying the first-semester GPAs of 2000 college freshman? Pie chart Bar graph Histogram

Histogram

The assumption we make about the null hypothesis in statistical hypothesis testing is similar to the principle in the court system that one is "innocent until proven guilty."

True

Use this information to answer the next three questions. To discourage students from driving to campus, a university claims students spend an average of 20 minutes looking for a parking spot. Students believe the actual time is less than this. After taking a random sample of 45 students, a sample mean of 17.4 minutes to find a parking spot was calculated. To assess the evidence provided by the sample data, what is the appropriate question to ask? Is the true mean amount of time needed to find a parking spot 17.4 minutes? How likely is it that the true mean amount of time needed to find a parking spot is 20 minutes? How likely is it that, in a sample of 45, the calculated mean amount of time needed to find a parking spot is 17.4 minutes or less if the true mean is 20? How likely is it that, in a sample of 45, the calculated mean amount of time needed to find a parking spot is less than 20 minutes?

How likely is it that, in a sample of 45, the calculated mean amount of time needed to find a parking spot is 17.4 minutes or less if the true mean is 20?

Use this scenario to answer the next three questions. One of your professors claims 90% of BYU students are currently enrolled in a religion course. To test this claim, you randomly sample 300 BYU students and find that only 78% of them are enrolled in a religion course. Based on these sample results, you have evidence against your professor's claim. What type of statistical inference did you use? Point estimation Interval estimation Hypothesis testing

Hypothesis testing

The radius of a wheel on a toy car is supposed to be 3 4 of an inch. If the wheel is too small or too large, the car will not roll properly. The manufacturer measures the radius in a random sample of 20 cars to determine whether the mean radius of the wheels currently being produced is different from 3 4 of an inch. Select the correct null and alternative hypotheses for this test. H​0 :​ μ = 3 4 in. versus Ha : μ ≠ 3 4 in. H​0 :​ μ = 3 4 in. versus Ha : μ < 3 4 in. H​0 :​ μ = 3 4 in. versus Ha : μ > 3 4 in. H​0 :​ x̅ = 3 4 in. versus Ha : x̅ ≠ 3 4 in. H​0 :​ x̅ = 3 4 in. versus Ha : x̅ < 3 4 in. H​0 :​ x̅ = 3 4 in. versus Ha : x̅ > 3 4 in.

H​0 :​ μ = 3 4 in. versus Ha : μ ≠ 3 4 in.

Studies have shown the average life span of an adult male in the United States is 78 years. A sociologist believes that the average life span of an adult male in the state of Utah to be slightly higher. What hypotheses should he test? H​0 ​: x̄ = 78 vs. Ha : x̄ ≠ 78 H​0 ​: x̄ = 78 vs. Ha : x̄ < 78 H​0 ​: x̄ = 78 vs. Ha : x̄ > 78 H​0 ​: μ = 78 vs. Ha : μ ≠ 78 H​0 ​: μ = 78 vs. Ha : μ > 78 H​0 ​: μ = 78 vs. Ha : μ < 78

H​0 ​: μ = 78 vs. Ha : μ > 78

The average time required to assemble a gas barbecue grill has been one hour and twenty minutes (80 minutes). An employee for the company has an idea that she thinks will shorten the time required for assembly. What hypotheses should be tested to determine whether her idea works? H​0 ​: x̄ = 80 vs. Ha : x̄ ≠ 80 H​0 ​: x̄ = 80 vs. Ha : x̄ < 80 H​0 ​: x̄ = 80 vs. Ha : x̄ > 80 H​0 ​: μ = 80 vs. Ha : μ ≠ 80 H​0 ​: μ = 80 vs. Ha : μ > 80 H​0 ​: μ = 80 vs. Ha : μ < 80

H​0 ​: μ = 80 vs. Ha : μ < 80

The existence of possible lurking variables is the main reason we say association does not imply causation.

True

Three of the following are correct statements about probabilities and one statement is incorrect. Which statement is NOT correct? All probabilities must be between zero and one inclusive. The probability that an event does not occur equals one minus the probability that the event does occur. The sum of the probabilities from all possible outcomes equals one. If two events cannot occur simultaneously, then the probability that either occurs cannot be computed.

If two events cannot occur simultaneously, then the probability that either occurs cannot be computed.

Consider the following confidence interval interpretation: "There is a 98% chance that the true mean laptop screen size lies between 12.47 and 15.59." Is this interpretation of a confidence interval correct or incorrect? Why or why not? Correct. It gives all three parts of confidence interval interpretation Incorrect. It does not give the level of confidence correctly Incorrect. It does not state that the value of the population parameter is in the confidence interval Incorrect. It does not give the actual confidence interval

Incorrect. It does not give the level of confidence correctly

Consider the following confidence interval interpretation: "90% of the time the true mean number of Utah high school students involved in a car accident per month falls between 1523.78 and 1539.56." Is this interpretation of a confidence interval correct or incorrect? Why or why not? Incorrect. It does not state the confidence level correctly Incorrect. It does not give the actual confidence interval Correct. It gives the three parts of a confidence interval interpretation Incorrect. It does not state that the value of the population parameter is in the confidence interval

Incorrect. It does not state the confidence level correctly

If we set α = 0.05, what can we do to increase power? Increase sample size. Decrease sample size. Increase the probability of a Type II Error.

Increase sample size.

Which of the following is NOT a measure of center of the data? Interquartile range Median Mean

Interquartile range

A study of child preferences for milk chocolate was performed. Based on sample results, researchers were 95% confident that the proportion of children that liked milk chocolate was between .75 and .93. What type of inference is being used? Interval estimation Hypothesis testing Point estimation

Interval estimation

A tire manufacturer has a 60,000 mile warranty for tread life. The manufacturer considers the overall tire quality to be acceptable if less than 8% are worn out at 60,000 miles. A study was done and researchers were 98% confident that the proportion of tires that are worn out at 60,000 miles lies between 7.8% and 9.6%. What type of statistical inference is this? Interval estimation Point estimation Hypothesis testing

Interval estimation

Based on sample results, we are 90% confident that the mean travel time to work for workers 16 and older is between 16.8 and 25.4 minutes. What type of inference is this? Point estimation Interval estimation Hypothesis testing

Interval estimation

If the distribution of data is symmetric, then the mean of the data ___________ the median. Is greater than Is equal to Is less than Cannot be compared to

Is equal to

The following situation applies to the next four questions: The Federal Pell Grant Program provides need-based grants to low-income undergraduate and certain postbaccalaureate students to promote access to postsecondary education. According to the National Postsecondary Student Aid Study conducted by the U.S. Department of Education in 2008, the average Pell grant award for 2007-2008 was $2,600. Assume that the standard deviation, σ, in Pell grant awards was $500 and that the distribution of awards is left skewed. Suppose we take a random sample of size 20. What is the probability that the mean of the 20 awards is greater than $2,700? 0.8133 It is not appropriate to calculate probabilities in this situation. 0.8944 0.1867 0.1056

It is not appropriate to calculate probabilities in this situation.

Which of the following statements correctly describes a normal curve? Its mean is not equal to its median. Its standard deviation is always one. It is symmetric.

It is symmetric.

Four of the following statements are correct descriptions of a Normal curve. Which one is NOT a characteristic of a Normal curve? It is symmetric Its spread increases as its mean increases It is bell-shaped Its mean is equal to its median It is single-peaked (unimodal)

Its spread increases as its mean increases

For random samples of size n = 100, what is the standard deviation of the sampling distribution of x̅? Less than 20 Greater than 20 Equal to 20

Less than 20

What two things do we need in order o compute margin of error for a one-sample t confidence interval for μ? Sample size and level of confidence. Level of confidence and the standard error of x̅. Values for μ and α. The mean and standard deviation of the sampling distribution of x̅

Level of confidence and the standard error of x̅.

What is the alternative hypothesis in this example? Male and female scholarship athletes have the same mean GPA Female scholarship athletes have a higher mean GPA than male scholarship athletes Mean GPA of scholarship athletes is related to gender Male and female scholarship athletes do not have the same mean GPA

Male and female scholarship athletes do not have the same mean GPA

The following situation applies to the next five questions: In order to determine if there is a difference between the mean GPA of male and female scholarship athletes, a university administrator obtains a sample of the academic records of past and present scholarship athletes at the university. The administrator reports that the mean GPA (grade point average) of a random sample of 40 male scholarship athletes is 3.02 and the mean GPA of a random sample of 36 female scholarship athletes is 3.11. If there is no difference in the mean GPA of male and female athletes, the probability of obtaining this difference (3.11 - 3.02 = 0.09) or more extreme is approximately 0.287. What is the null hypothesis in this example? Male and female scholarship athletes do not have the same mean GPA Male and female scholarship athletes have the same mean GPA Female scholarship athletes have a higher mean GPA than male scholarship athletes Mean GPA of scholarship athletes is related to gender

Male and female scholarship athletes have the same mean GPA

Store B does not agree with the results of the study. After looking into it, the manager discovers that receipts were taken from the first 100 shoppers at each store on a certain day of the week. Based on this information, should Store B trust the results of this study? Yes, because a large sample (100 receipts) was taken from each store. No, because the receipts were not collected randomly. Yes, because the results were significant. No, because receipts weren't collected from every transaction at each store.

No, because the receipts were not collected randomly.

Are the conditions of randomness and normality met for this test? How? No, because it was a random sample No, because the sample data was not plotted and it was not stated that the population is normal Yes, because it was a random sample and the sample size was large enough to apply the Central Limit Theorem Yes, because it was a random sample and the population is stated to have a normal distribution

No, because the sample data was not plotted and it was not stated that the population is normal

Suppose the student is only able to sample 25 students from the class. Can he still calculate the probability of getting an average test score higher than 84? Why or why not? Yes, because he has enough data to calculate a mean. Yes, because his sample size is large enough. No, because the sample size is not large enough. No, because that sample does not represent the population.

No, because the sample size is not large enough.

Suppose a survey is so long that many respondents refuse to complete it. What type of bias could result? Undercoverage Bias Response Bias Non-Response Bias Question-wording Bias

Non-Response Bias

Which of the following shows the conditions that must be met by one-sample t procedures? Normality of the population or n > 30, and a randomized experiment Randomized experiment and n > 30 Normality of the sample and randomness in the data collection Normality of the population or large sample size, and randomness in the data collection

Normality of the population or large sample size, and randomness in the data collection

The following scenario applies to questions 7 through 9: Suppose we have a right-skewed population distribution with a mean of 222 and a standard deviation of 33. For random samples of size 19, what will be the shape of the sampling distribution of x̅? Not approximately Normal - the Central Limit Theorem does not apply Normal Approximately Normal

Not approximately Normal - the Central Limit Theorem does not apply

A researcher wishes to estimate the mean amount of money single, undergraduate college students spend on food in a typical month. To generate a sample, she calls the first 120 students listed in the directory of the local college. Is it safe to compute a confidence interval from this sample? Yes—the sample is large (n>30) Yes—the sample was collected randomly No—the sample is small No—the sample was not collected randomly

No—the sample was not collected randomly

Refer to the situation above. Suppose the researcher actually believed the true mean is much lower than 3.02. What type of test should be conducted? One-sided upper-tailed test One-sided lower-tailed test Two-sided test

One-sided lower-tailed test

Does ripping off a band-aid hurt less than slowly pulling it off? Researchers plan to compare the two methods by applying two medium sized band-aids to the underside of the right forearm of each of 50 volunteer subjects. One band-aid will be randomly selected to be pulled off with a quick yank while the other will be gently peeled off. The order in which the band-aids are removed will also be randomized. After each band-aid is removed, the subject will be asked, "On a scale of 0 to 10, how much did the removal hurt?" with zero for "no pain" and 10 for "the worst pain imaginable." What is the response variable? Pain score Band-aid size Which band-aid was removed first Method of band-aid removal

Pain score

Patients often show improvement even when they get a sugar pill from a doctor rather than the actual medication. What is this phenomenon called? Placebo effect Hawthorne effect Confounding Bias

Placebo effect

Scientists want to investigate the effects caffeine on short term memory by randomly assigning 200 volunteers to intake 86mg of caffeine before a memory quiz and the remaining 200 volunteers to intake 86mg of a placebo before taking a memory quiz. The quiz score of each volunteer is recorded. What is the response variable? Caffeine Placebo Quiz Score

Quiz Score

Which one of the following is a benefit of randomized block designs (RBD)? RBD eliminates all lurking variables. RBD reduces chance variation by removing variation associated with the blocking variable. RBD removes all bias. RBD eliminates the placebo effect.

RBD reduces chance variation by removing variation associated with the blocking variable.

Researchers want to compare the effectiveness of exercise and dieting compared to dieting alone for weight loss. They have 60 volunteers, 30 men and 30 women. They randomly assign half of the men to Group 1, exercise and diet, and the other half to Group 2, diet alone. They follow the same procedure for the women. Half of the women are assigned to Group 1 and the other half are assigned to Group 2. After 16 weeks, their weight loss was measured and compared. What type of study is this? Observational Study Randomized Controlled Experiment Matched Pairs Experiment Randomized Block Experiment

Randomized Block Experiment

A study was conducted to test the effectiveness of using an antidepressant called imipramine in treating bulimia, an eating disorder. Twenty patients were randomly assigned to one of two groups with ten in each. One group received imipramine and the other received a placebo. The response measured was binge frequency. What type of study is this? Observational Study Randomized Controlled Experiment Matched Pairs Experiment Randomized Block Experiment

Randomized Controlled Experiment

Because of concerns about employee obesity and related health problems, a very large company conducted a study to compare two weight-reducing programs (low-carb diet and low-fat diet). Forty employees volunteered to participate in the study for a 10-week period. Half of the employees were randomly assigned to the low-carb diet and the other half randomly assigned to the low-fat diet. What type of study is this? Observational Study Randomized Controlled Experiment Randomized Block Experiment Matched Pairs Experiment

Randomized Controlled Experiment

Referring to question 5, Suppose α =0.10 rather than 0.05. What should the researcher conclude? Reject the null hypothesis. The average time full-time corporate employees work per week is greater than 40 hours. Reject the null hypothesis. The average time full-time corporate employees work per week is 40 hours. Fail to reject the null hypothesis. The average time full-time corporate employees work per week is 40 hours. Fail to reject the null hypothesis. There is insufficient evidence to conclude the average time full-time corporate employees work per week is greater than 40 hours.

Reject the null hypothesis. The average time full-time corporate employees work per week is greater than 40 hours.

What is the major difference between an observational study and an experiment? Subjects choose their treatment in an experiment. Researchers assign treatments to subjects in an experiment. Experiments frequently have confounding between two variables in their effect on the response variable.

Researchers assign treatments to subjects in an experiment.

Which of the following describes a valid sampling procedure? An interviewer uses a set of personal criteria to pick respondents. Respondents are chosen by an impersonal chance device. Individuals, not the researcher, choose who will be in the sample. The first 50 people at a shopping mall are selected.

Respondents are chosen by an impersonal chance device.

Use this information to answer the next two questions. Suppose we are testing the following hypotheses: H0: It is not your friend's birthday. Ha: It is your friend's birthday. What constitutes a type I error for these hypotheses? Saying nothing when it is in fact their birthday. Saying nothing when it isn't their birthday. Saying "Happy Birthday" when it is in fact their birthday. Saying "Happy Birthday" when it isn't their birthday.

Saying "Happy Birthday" when it isn't their birthday.

What constitutes a type II error for these hypotheses? Saying nothing when it is in fact their birthday. Saying nothing when it isn't their birthday. Saying "Happy Birthday" when it is in fact their birthday. Saying "Happy Birthday" when it isn't their birthday.

Saying nothing when it is in fact their birthday.

Your company markets a computerized medical diagnostic program used to evaluate thousands of people. The program scans the results of routine medical tests (pulse rate, blood tests, etc.) and refers the case to a doctor if there is evidence of a medical problem. The program makes a decision about each person. The hypotheses are: H0: The patient is healthy. Ha: The patient has a medical problem. Which of the following describes a Type I error in this situation? Not referring a patient with a medical problem to the doctor. Sending a patient with a medical problem to the doctor. Sending a healthy patient to the doctor. Not referring a healthy patient to the doctor.

Sending a healthy patient to the doctor.

A computer manufacturer has just received a shipment of 8000 computer chips. In order to ensure that the shipment meets their quality standards, they want to sample a few chips and make a detailed examination of the sample. The chips are packaged individually and have serial numbers. If they use a statistical software package to randomly select serial numbers for 20 chips for inspection, what type of sampling is this? Simple random sample Stratified sample Convenience sample Multistage sample

Simple random sample

What is the alternative hypothesis in this example? The mean amount of time needed to find a parking spot is 20 minutes. The mean amount of time needed to find a parking spot is 17.4 minutes. The mean amount of time needed to find a parking spot is less than 20 minutes. The mean amount of time needed to find a parking spot is less than 17.4 minutes.

The mean amount of time needed to find a parking spot is less than 20 minutes.

A student in Stat 121 wants to estimate the mean score on the Stat 121 final exam from last semester. They asked 200 students who took the class last semester what their final exam score was and recorded it. What is the sample? A subset of students currently enrolled in Stat 121 The 200 students interviewed All students who took Stat 121 last semester All BYU students

The 200 students interviewed

A state representative wants to know how voters in his district feel about enacting a statewide smoking ban in all enclosed public places, including bars and restaurants, as well as several other current statewide issues. He mails a questionnaire addressing these issues to an SRS of 800 voters in his district. Of the 800 questionnaires mailed, 290 were returned. What is the sample in this study? The 800 voters who received the questionnaire. The 290 voters who returned the questionnaire. All voters in his district.

The 290 voters who returned the questionnaire.

Which hypothesis does the researcher generally want to prove? The null hypothesis. The alternative hypothesis. The claimed hypothesis. The significant hypothesis.

The alternative hypothesis.

Refer to the above question. Suppose x̄ = 50.15 bushels per acre. Graphically, what represents the ​P-​ value? The area under the sampling distribution of x̄ curve between 50 and 50.15. The area under the sampling distribution of x̄ curve to the left of 50.15. The area under the sampling distribution of x̄ curve to the right of 50.15. The probability that H0 is true if x̄ = 50.15.

The area under the sampling distribution of x̄ curve to the right of 50.15.

The Wechsler Adult Intelligence Scale (WAIS) is the most common "IQ" test. The scale of scores is approximately Normal with mean 100 and standard deviation 15. Which of the following is the best interpretation of the standard deviation? The balancing point of the histogram of IQ scores is 15. The difference between the lowest and the highest IQ scores is 15. The average distance between an individual's IQ score and 100 is 15. The range of the middle 50% of IQ scores is 15.

The average distance between an individual's IQ score and 100 is 15.

Use this information to answer the next three questions. A sample of 100 sales receipts is taken from two competing grocery stores. Store A has a mean total of $49.60 on each receipt and Store B has a mean total of $50.23 on each receipt. Store B claims they have a higher mean total per customer than Store A. If there is no difference between the two stores, the probability of obtaining this difference (49.60 - 50.23 = 0.63) is 0.356. With a p-value of 0.356, what is the appropriate conclusion to make? The data provides strong evidence to reject H0. The data provides strong evidence to accept H0. The data does not provide strong evidence to reject H0. The data does not provide strong evidence to accept H0.

The data does not provide strong evidence to reject H0.

Which one of the following is ​NOT​ synonymous with "Reject H​0"​ ? Results are statistically significant. p-value < α Conclude Ha is correct. The results are due to chance.

The results are due to chance.

Statistically significant​ is equivalent to all of the following ​except​ one. Which ​one​ is not equivalent? p-value < α The difference between the observed value of the statistic and the value of the parameter as given in H​0​ is too large to attribute to just chance variation. The probability of obtaining a sample statistic as extreme or more extreme than actually observed if H​0​ were true is too small for us to believe that H​0​ is correct. The observed statistic is inconsistent with the null hypothesis. The difference between an observed statistic and the true parameter value is due to chance variation.

The difference between an observed statistic and the true parameter value is due to chance variation.

Suppose a sample of size 250 was taken instead of 100. How will the margin of error change? The margin of error will not change in size The margin of error will increase in size The margin of error will decrease in size

The margin of error will decrease in size

Suppose the researchers decided to take a sample of 500 rather than 1005, how would this change the margin of error? The margin of error would not change The margin of error would decrease The margin of error would increase

The margin of error would increase

Referring to question 43, the mean of the sample is 173 mg and the margin of error for the confidence interval given in the above question is 21 mg. Which ​one​ of the following is a correct interpretation of margin of error? 95% of the time, 173 will differ from the true average weekly oral dose by 21 mg. The figure given as 173 is not the exact value; 173 may fluctuate anywhere between 152 and 194. The maximum difference we expect between our sample result and the true average weekly oral dose is no more than 21 mg. 95% of the time, the responses of all body builders will be within 21 mg of 173 mg.

The maximum difference we expect between our sample result and the true average weekly oral dose is no more than 21 mg.

Which is an appropriate interpretation of the margin of error? The confidence level for estimating a population parameter The maximum likely distance between a point estimator and the parameter it estimates Choices A, B and C are all true The typical distance between the sample proportion and the population proportion The standard deviation of the sampling distribution of a statistic

The maximum likely distance between a point estimator and the parameter it estimates

In order to estimate the mean age to be diagnosed with diabetes, a researcher takes a sample and finds the mean age to be 16.4. What is the parameter of interest? The mean age of diagnoses of the sample The proportion of all people who are diagnosed at the age of 17 The proportion of the sample of people who were diagnosed at the age of 17 The mean age of all people at which they were diagnosed with diabetes

The mean age of all people at which they were diagnosed with diabetes

In order to estimate the mean age to be diagnosed with diabetes, a researcher takes a sample and finds the mean age to be 16.4. What statistic is used to estimate the parameter of interest? The proportion of all people who are diagnosed at the age of 17 The mean age of diagnoses for the sample The proportion of the sample of people who were diagnosed at the age of 17 The mean age of all people at which they were diagnosed with diabetes

The mean age of diagnoses for the sample

The following situation applies to the next 6 questions: In the 2004 election in Utah, 66% of all Utah voters voted for Amendment 3, the marriage amendment. Suppose a Statistics major decided to predict the sampling distribution of p̂ for samples of size 100 for this situation. What is the mean of the sampling distribution of p̂? The mean equals p, which is 66% The mean equals p̂, which is 66% The mean will equal p, but we don't know what the value of p is

The mean equals p, which is 66%

An administrator in a very large company wants to estimate the mean level of nitrogen oxides (NOX) emitted in the exhaust of a particular car model in their very large fleet of cars. Historically, nitrogen oxide levels have been known to be Normally distributed with a standard deviation of 0.15 g/ml. What statistic is used to estimate the parameter of interest? The standard deviation of the level of nitrogen oxide of all cars of a particular model in the very large fleet The mean level of nitrogen oxide of a sample of cars of a particular model in the very large fleet The mean level of nitrogen oxide of all cars of a particular model in the very large fleet.

The mean level of nitrogen oxide of a sample of cars of a particular model in the very large fleet

An administrator in a very large company wants to estimate the mean level of nitrogen oxides (NOX) emitted in the exhaust of a particular car model in their very large fleet of cars. Historically, nitrogen oxide levels have been known to be Normally distributed with a standard deviation of 0.15 g/ml. What is the parameter of interest that the administrator wants to estimate? The standard deviation of the level of nitrogen oxide of all cars of a particular model in the very large fleet. The mean level of nitrogen oxide of a sample of cars of a particular model in the very large fleet. The mean level of nitrogen oxide of all cars of a particular model in the very large fleet.

The mean level of nitrogen oxide of all cars of a particular model in the very large fleet.

What is the parameter the researchers are trying to estimate? The mean number of hours each week teenagers in their sample spent watching television The proportion of time each week teenagers in their sample spent watching television The mean number of hours each week all teenagers spend watching television The proportion of time each week all teenagers spend watching television

The mean number of hours each week all teenagers spend watching television

What is the statistic you are using to estimate the parameter of interest? The mean number of hours each week teenagers in their sample spent watching television The proportion of time each week teenagers in their sample spent watching television The mean number of hours each week all teenagers spend watching television The proportion of time each week all teenagers spend watching television

The mean number of hours each week teenagers in their sample spent watching television

Three children are in a room, ages 3, 4, and 5. A fourth child enters aged 4. What can we say about the mean and standard deviation of the ages? The mean stays the same, but the standard deviation increases. The mean stays the same, but the standard deviation decreases. The mean and standard deviation stay the same. Both the mean and standard deviation increase.

The mean stays the same, but the standard deviation decreases.

Use the following situation for questions 2-5: A manufacturing process produces bags of cookies. The weights of these bags are known to be normally distributed and should have a mean of μ = 15.0 ounces with a standard deviation of σ = 0.4 ounces. In order to monitor the process, four bags are selected periodically and their average weight (x̄) is computed. What is the parameter of interest? The mean weight of all bags of cookies produced by this manufacturing process. The weight of a bag of cookies produced by this manufacturing process. All bags of cookies produced by this manufacturing process. The mean weight of four bags of cookies produced by this manufacturing process.

The mean weight of all bags of cookies produced by this manufacturing process.

The following scenario applies to the next five questions: The weight of a carton of a dozen eggs produced by a certain breed of hens is supposed to be normally distributed with a mean of 780 grams. A quality manager randomly checks thirty-five cartons of eggs (n = 35) to see whether the mean weight differs from 780 grams. She finds x̄ = 796. What is the parameter of interest? The mean weight of all cartons of eggs produced by a certain breed of hens The weight of all cartons of eggs produced by a certain breed of hens The mean weight of 35 cartons of eggs produced by a certain breed of hens The mean weight of all eggs produced by a certain breed of hens

The mean weight of all cartons of eggs produced by a certain breed of hens

If we take samples of size 200 rather than 75, what will happen to the mean of the sampling distribution of x̄? The mean will decrease The mean will stay exactly the same The mean will be almost the same The mean will increase

The mean will stay exactly the same

What would happen to the mean of the sampling distribution of p̂ if the Statistics major predicted the sampling distribution of for samples of size 500 instead of size 100? The men would decrease The mean would stay the same The mean would increase

The mean would stay the same

If all possible samples of size 200 are taken instead of 100, how would this change the mean and standard deviation of the sampling distribution of x̅? The mean would stay the same and the standard deviation would decrease The mean would increase and the standard deviation would increase The mean would decrease and the standard deviation would increase The mean would increase and the standard deviation would decrease The mean would stay the same and the standard deviation would increase The mean would decrease and the standard deviation would decrease

The mean would stay the same and the standard deviation would decrease

If all possible samples of size 80 are taken from a population instead of size 20, how would this change the mean and standard deviation of the sampling distribution of x̅? The mean would stay the same and the standard deviation would decrease The mean would increase and the standard deviation would decrease The mean would decrease and the standard deviation would increase The mean would increase and the standard deviation would increase The mean would decrease and the standard deviation would decrease

The mean would stay the same and the standard deviation would decrease

Two studies were done on the same set of data, where study I was a one-sided test and study II was a two-sided test. The p-value of the test corresponding to study I was found to be 0.030. What is the p-value for study II? The p-value must be 0.015 The p-value must be 0.030 The p-value cannot be determined with the given information The p-value must be 0.060

The p-value must be 0.060

Three of the following statements about probability are correct. Which statement is incorrect? Probability is a way of quantifying uncertainty. The probability of an event ranges from -1 to 1. The closer the probability of an event is to zero, the less likely the event is to occur. The closer the probability of an event is to one, the more likely the event is to occur.

The probability of an event ranges from -1 to 1.

Assume that the p-value was calculated to be 0.03. Interpret this p-value in context. The probability of rejecting the null hypothesis is 0.03. The probability of getting a sample mean as extreme or more extreme than 796g is equal to 0.03 assuming the population mean is 780g. The probability that our sample mean of 796g is equal to the true population mean is 0.03. The probability of getting a sample mean more extreme than the one we observed (796g) is equal to 0.03 assuming the population mean is not 780g.

The probability of getting a sample mean as extreme or more extreme than 796g is equal to 0.03 assuming the population mean is 780g.

Which one of the following is a correct interpretation of the ​p-​value given in the above question? The probability that the null hypothesis is true is .013. The probability of rejecting a true null hypothesis is .013. The probability of obtaining a sample mean that exceeds the claimed mean value of 6.3 is .013. The probability of obtaining a sample mean that is as far or farther from the hypothesized mean value of 6.3 as the observed value of 6.8 is .013. The probability of getting a sample mean that is no more than 6.8 when the population mean is really 6.3 is .013.

The probability of obtaining a sample mean that is as far or farther from the hypothesized mean value of 6.3 as the observed value of 6.8 is .013.

Which of the following describes statistical power in this situation? The probability of not referring a patient with a medical problem to the doctor. The probability of sending a patient with a medical problem to the doctor. The probability of sending a healthy patient to the doctor. The probability of not referring a healthy patient to the doctor.

The probability of sending a patient with a medical problem to the doctor.

Which one of the following is NOT a parameter? The mean of the measurements on all the individuals in a population. The proportion of a population that have a certain characteristic. The standard deviation of an entire population. The proportion in a sample survey that favor a certain opinion.

The proportion in a sample survey that favor a certain opinion.

What is the statistic you are using to estimate the parameter of interest? The mean number of all BYU students currently enrolled in a religion course The proportion of all BYU students currently enrolled in a religion course The mean number of BYU students in your sample currently enrolled in a religion course The proportion of BYU students in your sample currently enrolled in a religion course

The proportion of BYU students in your sample currently enrolled in a religion course

What is the parameter of interest? The mean number of all BYU students currently enrolled in a religion course The proportion of all BYU students currently enrolled in a religion course The mean number of BYU students in your sample currently enrolled in a religion course The proportion of BYU students in your sample currently enrolled in a religion course

The proportion of all BYU students currently enrolled in a religion course

The following situation applies to the next 2 questions: In a study of religious practices among college students, a random sample of 127 students were interviewed; 107 of the students said that they pray at least once in a while. Which of the following best describes the parameter p? The proportion of all individuals in the population who are college students The proportion of all college students who say they are religious The proportion of all college students who believe in a higher power The proportion of all college students who say they pray at least once in a while

The proportion of all college students who say they pray at least once in a while

In statistics, how do we define the probability of an event? The relative frequency with which the event occurs in a long series of trials The ratio of one over the total number of possible outcomes

The relative frequency with which the event occurs in a long series of trials

A group of college students believed that herbal tea has remarkable restorative powers. To test their theory, they randomly selected residents at a local nursing home. Each week they visited these residents and served them herbal tea. After several months, many of these residents were more cheerful and healthy. Which of the following can be correctly concluded from this study? Herbal tea will improve the emotional state of residents in nursing homes. While there is some evidence that drinking herbal tea improves one's emotional state, the results are not convincing since a scientist did not conduct the study. The results are not convincing because only residents of one nursing home were studied and only for a few months. The results are not convincing because the effect of herbal tea is confounded with the effect of visiting.

The results are not convincing because the effect of herbal tea is confounded with the effect of visiting.

Which one of the following measures the variability of a statistic? The standard deviation of the data. The standard deviation of the sampling distribution for the statistic. The total sum of squared deviations of the observations about the mean. The number of standard deviations that a statistic value differs from the parameter value.

The standard deviation of the sampling distribution for the statistic.

What does s/√n estimate? The standard deviation of the sampling distribution of x-bar The standard deviation of the sample The standard deviation of the population The mean of the sampling distribution of x-bar

The standard deviation of the sampling distribution of x-bar

The standard deviation of a set of data is computed to be 8.2. If 10 is added to each data value, what can we say about the standard deviation of the new data set? The standard deviation decreases. The standard deviation increases. The standard deviation stays the same. Without recomputing the standard deviation, it is impossible to say.

The standard deviation stays the same.

If we take samples of size 200 rather than 75, what will happen to the standard deviation of the sampling distribution of x̄? The standard deviation will decrease The standard deviation will stay the same The standard deviation will increase

The standard deviation will decrease

What would happen to the standard deviation of the sampling distribution of p̂ if samples of size 500 were taken instead of samples of size 100? The standard deviation would decrease The standard deviation would increase The standard deviation would stay the same

The standard deviation would decrease

A 98% confidence interval estimate for the mean nitrogen oxide level was computed. What do we hope to find in this confidence interval? The value of μ, the mean level of nitrogen oxides emitted by all cars of a particular model. 98% of the nitrogen oxide levels. The value of x̄, the mean nitrogen oxide level in the sample of a particular model of cars. The standard level of confidence.

The value of μ, the mean level of nitrogen oxides emitted by all cars of a particular model.

What is the correct description of the median of a distribution that is described by a density curve? The value in the data set that occurs with the highest frequency The point that is intermediate between interquartile range and standard deviation The value that divides the area of the density curve in half The point at which the distribution "balances"

The value that divides the area of the density curve in half

Researchers followed a group of 10,892 middle-aged adults over a period of nine years. They found that smokers who quit had a higher risk of diabetes within three years of quitting than either nonsmokers or continuing smokers. Does this show that stopping smoking causes the short-term risk for type 2 diabetes to increase? This is an observational study; it is not reasonable to conclude any cause-and-effect relationship. This is an experiment; it is reasonable to conclude a cause-and-effect relationship.

This is an observational study; it is not reasonable to conclude any cause-and-effect relationship.

Which of the following random variables is continuous? Time required to run a mile Number of children in a family Number of books on a shelf

Time required to run a mile

Suppose you are testing the following hypotheses. What is the type I error for these hypotheses? H​0 :​ Cake is not done, versus H​a:​ Cake is done To believe that the cake is not done when it is still not done. To believe that the cake is not done when it really is done. To believe that the cake is done when it is still not done. To believe that the cake is done when it really is done.

To believe that the cake is done when it is still not done.

What is the purpose of a statistical control chart? To determine whether distributions are Normal or not. To measure the biases in an observational study. To distinguish between natural and unnatural variation. To assess relationships between variables.

To distinguish between natural and unnatural variation.

Why do we randomize in experiments? To eliminate bias associated with lurking variables. To enhance the placebo effect. To enable the measurement of treatment differences. To remove extraneous variation from the experiment error. To more precisely measure chance variation.

To eliminate bias associated with lurking variables.

Why do we compare different treatment groups in experiments? To eliminate bias associated with lurking variables. To enhance the placebo effect. To enable the measurement of treatment differences. To remove extraneous variation from the experiment error. To more precisely measure chance variation.

To enable the measurement of treatment differences.

What is the purpose of a confidence interval? To measure the amount of confidence you have in your interval. To determine the percentage of times the parameter will fall into your interval. To estimate the value of a parameter. To give a range of reasonable probability simulations.

To estimate the value of a parameter.

Why do we use replication in experiments? To eliminate bias associated with lurking variables. To enhance the placebo effect. To enable the measurement of treatment differences. To remove extraneous variation from the experiment error. To more precisely measure chance variation.

To more precisely measure chance variation.

The explanatory variable is: Body weight in kilograms. Dosage in milligrams of ephedrine. Number of revolutions of the exercise wheel. Effect of ephedrine on the rate. Species of rat. Treatment of ephedrine versus no ephedrine.

Treatment of ephedrine versus no ephedrine.

For perfectly symmetric data, the mean exactly equals its median.

True

If the p-value is less than α, then the results are statistically significant.

True

Increasing the confidence level will lead to a wider margin of error.

True

Probabilities on individuals can only be computed using the standard Normal table if the population is Normally distributed.

True

Samples can be biased due to poor interviewing and/or poorly worded questions.

True

Samples of convenience are non-probability samples.

True

Standard deviation is a measure of variability.

True

Refer to the previous question. Even though Jane randomly selects students, her survey is biased because not all students take religion classes every semester. What type of bias is this? Undercoverage bias Non-response bias Question wording bias Interviewer bias

Undercoverage bias

Which one of the following does ​NOT​ affect margin of error for a one-sample ​t confidence interval for μ? (Assume that the necessary conditions are met.) Level of confidence Sample size Standard error of x̄ Value of the parameter μ

Value of the parameter μ

Suppose researchers calculated a 90% confidence interval to be (0.60, 0.68). What is the correct interpretation of this interval? We are 90% confident that the true proportion of adults that were aware of Viagra after one week lies between 0.60 and 0.68. 90% of adults fall between 0.60 and 0.68. The is a 90% probability that the true proportion of adults that were aware of Viagra after one week lies between 0.60 and 0.68. We are 90% confident that the true sample proportion of adults that were aware of Viagra after one week lies between 0.60 and 0.68.

We are 90% confident that the true proportion of adults that were aware of Viagra after one week lies between 0.60 and 0.68.

The weekly oral dosage of anabolic steroids was measured on a sample of 20 body builders. A 95% confidence interval estimate for the average weekly oral dose of anabolic steroids obtained from these results was 152 mg to 194 mg. Which ​one​ of the following is a correct interpretation of this confidence interval? There is a .95 probability that the average weekly dose of anabolic steroids used by body builders is between 152 mg. and 194 mg. We are 95% confident that the average weekly dose of anabolic steroids used by all body builders is between 152 mg. and 194 mg. We are 95% confident that the average weekly dose of anabolic steroids used by the 20 body builders is between 152 mg. and 194 mg. 95% of the time, the average weekly dose of anabolic steroids used by body builders is between 152 mg. and 194 mg. 95% of all body builders use between 152 mg. and 194 mg. of anabolic steroids per week.

We are 95% confident that the average weekly dose of anabolic steroids used by all body builders is between 152 mg. and 194 mg.

Does this study incorporate the principle of control/comparison? Yes, because the group of students receiving only traditional instruction can be considered a control group. The group of students receiving the additional instruction of probability-statistics can be considered the active treatment comparison group. No, because there was not a group of students who did not receive any instruction.

Yes, because the group of students receiving only traditional instruction can be considered a control group. The group of students receiving the additional instruction of probability-statistics can be considered the active treatment comparison group.

Lifetimes of a particular flashlight battery have a non-Normal distribution with mean, ​μ​, of 35.6 hours and standard deviation ​σ = 5.4 hours. A quality inspector is planning to take a random sample of 43 of these batteries and compute the sample mean. Can he compute the probability that the sample mean will be below 35.7 hours using the standard Normal table? Why or why not? Yes, because the sample will be large and random so the Central Limit Theorem applies. Yes, because the original population was normally distributed and sample will be random. No, because the sample size is too small to apply the Central Limit Theorem. No, because the original distribution was not normally distributed.

Yes, because the sample will be large and random so the Central Limit Theorem applies.

Is the normality condition met for this test? Yes, since the sample size is large Yes, since the population is known to be normally distributed No, since the sample size is small No, since the population is not known to be normally distributed

Yes, since the sample size is large

Which of the following can be considered a population? Select all that apply. all students at BYU all pigeons in Utah some students from BYU's STAT121 class None of these

all students at BYU all pigeons in Utah

A student in STAT121 wants to estimate the mean score on the STAT121 final exam from last semester. They asked 200 students who took the class last semseter what their final exam score was and recorded it. What is the population of interest? the sample of 200 students all BYU students all students currently in STAT121 all students who took STAT121 last semester

all students who took STAT121 last semester

The report about water quality included information on the water quality at swimming beaches in California. Forty-five of these beaches were sampled to test whether they failed to meet water quality standards. What is the population? all beaches in California all swimming beaches in California the 45 beaches that were sampled all beaches that fail the water quality test

all swimming beaches in California

The ________ hypothesis generally represents what the researcher wants to check, or suspects might actually be the case. null alternative

alternative

On August 27, 1995, an article in the Los Angeles Times reported that in a survey of 3297 California adults, 2780 (83.4%) had health insurance coverage. These results have a margin of error of ±1.4%. What type of study is being described? an observational study an experiment

an observational study

What is the shape of the sampling distribution of p̂ for samples of size 100? left-skewed right-skewed cannot be determined based on the given information approximately normal

approximately normal

The margin of error in a confidence interval covers only which kind of errors? interviewer errors chance errors due to random sampling bias errors due to wording of questions computational errors

chance errors due to random sampling

Suppose a researcher is interested in the average ACT score for high school students in Illinois. She randomly selects 150 high schools and then asks each student in the selected high schools what their ACT score was. What kind of sample is this? simple random sample (SRS) stratified sample cluster sample multistage sample

cluster sample

When we perform a proper experiment, we can establish causation. obtain biased results for the sample statistics. Produce experimental results that are confounded with the explanatory variable. More readily extend the results to the population than with surveys implement blocking - something that is NOT possible with surveys.

establish causation.

Fill in the blank: The purpose of a confidence interval is to provide _________. information about the range of data in a distribution a measure of the confidence we can have in our sample results representing the population a list of all possible values of the statistic from all possible samples plausible values that a parameter could take

plausible values that a parameter could take

Whenever performing a one sample ​t​ procedure on means, we should check for randomization and no outliers in the data. random allocation of individuals to treatments. only randomization. randomization and small sample sizes.

randomization and no outliers in the data.

Consider this formula for a confidence interval when σ is unknown: x̅±t(s/√n) Which part of this formula is the standard error of x-bar? t (s/√n) s s/√n None of these

s/√n

Which of the following is the correct formula for the standard error of x ¯? x = (− b ± √[b 2 − 4 a c])/2 a s/√n σ/√n

s/√n

Control charts are designed to sound an alarm when the amount of observed variation exceeds the amount that could be attributable to natural variation. variation is observed in the x̅'s the observed sample means differ from the control standard by an amount attributable to natural variation. the sample mean, x̅, differs from the control standard by even a small amount.

the amount of observed variation exceeds the amount that could be attributable to natural variation.

When using a confidence interval to perform a two-sided test, H​0​ will be rejected whenever the claimed parameter value in H​0​ falls inside the confidence interval. the observed statistic value from the sample falls inside the confidence interval. the claimed parameter value in H​0​ falls outside the confidence interval. the observed statistic value from the sample falls outside the confidence interval.

the claimed parameter value in H​0​ falls outside the confidence interval.

Sample results are said to be ​statistically significant​ whenever the difference between the observed statistic and the claimed parameter value given in H​0​ is too large to be due to chance. the difference between the true situation and the observed situation could plausibly have resulted because H​0​ is false. the researcher subjectively classifies the observed deviation from what was expected under H​0​ as large enough to matter. the difference between the observed statistic and the claimed parameter value is large enough to be worth reporting.

the difference between the observed statistic and the claimed parameter value given in H​0​ is too large to be due to chance.

Two variables are confounded when they interact in their effects on the response variable. the effect of one variable impacts the other variable. the effect of one variable on the response variable cannot be separated from the effect of the other variable on the response variable. both variables are classified as lurking variables

the effect of one variable on the response variable cannot be separated from the effect of the other variable on the response variable.

Standard error of x̄ refers to the amount an observed statistic for x̄ differs from its parameter, μ. the estimate of the standard deviation of the sampling distribution of x̄. the number of standard deviations that the observed statistic, x̄, differs from its parameter, μ. the maximum amount that a statistic, x̄, differs from its parameter, μ.

the estimate of the standard deviation of the sampling distribution of x̄.

A test of significance is intended to assess the evidence provided by data against the alternative hypothesis in favor of the null hypothesis. the evidence provided by data against the null hypothesis in favor of the alternative hypothesis. the probability that the null hypothesis is true. the probability that the alternative hypothesis is true.

the evidence provided by data against the null hypothesis in favor of the alternative hypothesis.

The probability of an event can be defined as 1 / k where k is the number of possible outcomes of which the event is one possible outcome. the fraction of times the event will occur if the random phenomenon is repeated many times. The number of successes. the odds of the event occurring; i.e., k to 1.

the fraction of times the event will occur if the random phenomenon is repeated many times.

Margin of error for 99% confidence tells us how much the measurements deviate from the unknown parameter mean. the most a statistic differs from the parameter for the middle 99% of all possible statistic values. the difference between the observed statistic and the unknown parameter value. how many standard deviations the observed statistic is from the unknown parameter value.

the most a statistic differs from the parameter for the middle 99% of all possible statistic values.

Level of confidence can be defined as the probability that a computed confidence interval contains the unknown parameter value. the percentage of time that the observations or measurements fall in the confidence interval. the probability that the observed statistic is in the confidence interval. the percentage of the time that the procedure will produce intervals that contains the parameter value.

the percentage of the time that the procedure will produce intervals that contains the parameter value.

Fill in the blank: The t-distribution with 6 degrees of freedom has ___________the standard Normal distribution. the same center but is less spread out than the same center and spread as the same center but is more spread out than

the same center but is more spread out than

Fill in the blank: The t-distribution with 8 degrees of freedom has ____________________ the standard Normal distribution. the same center but is more spread out than the same center but is less spread out than the same center and spread as a different center and a different spread than

the same center but is more spread out than

What is the random variable of the sampling distribution of x̅ ? the parameter being estimated the response variable the observations in the sample the sample mean

the sample mean

The Central Limit Theorem says that the sample mean x̄ gets closer and closer to μ as sample size increases. the sampling distribution of x̄ is approximately Normal when the sample size is large. the population from which we sample can be transformed to a Normal distribution using standard scores (z-scores). the shape of the histogram of observations in a sample gets more and more Normal as sample size increases.

the sampling distribution of x̄ is approximately Normal when the sample size is large.

Tests of significance on μ and confidence intervals for μ (with σ known) are based on the sampling distribution of x̄. the shape of the population distribution. the Law of Large Numbers. the language of sample designs.

the sampling distribution of x̄.

The Central Limit Theorem tells us that under certain conditions the shape of the histogram of the sample data will have the same shape as the population from which the sample was taken. the mean and standard deviation of the sample will be approximately equal to the mean and standard deviation of the population from which we sample. the shape of the population from which we sample will be approximately Normal. the shape of the data in the sample will be approximately Normal. the shape of the sampling distribution of x̄ will be approximately Normal.

the shape of the sampling distribution of x̄ will be approximately Normal.

The theoretical sampling distribution of a statistic consists of the results of a sample. the values of a statistic from all possible samples. the range of the values in a sample. a set of sample data that has the same shape as the original population.

the values of a statistic from all possible samples.

The standard deviation of the sampling distribution of x̅ measures the variability of observations about the mean. the variability of the sample mean values about the parameter, μ. the height of the sampling distribution. the error or difference between the value of a statistic and its parameter.

the variability of the sample mean values about the parameter, μ.

We use a t-distribution with n-1 degrees of freedom rather than the standard normal distribution whenever the Central Limit Theorem does not apply. we are using s to estimate σ. the population is not Normally distributed. we can apply the Law of Large numbers and do not need normality.

we are using s to estimate σ.

Which of the following is the correct formula for a confidence interval? x ¯ ± t ∗ σ n x ¯ ± σ n x ¯ ± z ∗ σ x ¯ ± t ∗ s n

x ¯ ± t ∗ s n

The sample mean, ________, is used to estimate the population mean, _________. s, σ p-hat, p μ, x̄ x̄, μ

x̄, μ

Fill in the blank: Central Limit Theorem allows us to compute probabilities on ___________ using the standard Normal table provided the sample size of the random sample is sufficiently large. x̅ μ s sample measurements

x̅

What is the probability of making a type II error? β 1 - β 1 - α α

β

The time it takes college freshman to complete the Mason Basic Reasoning Test is normally distributed with a mean of 24 minutes and a standard deviation of 5 minutes. What symbol should be used to represent the mean of 24 minutes? σ s μ x̄

μ

Which one of the following is not a statistic? μ x̅ n s median of data in a sample

μ

Which of the following intervals corresponds to the smallest area under a Normal curve? Q1 to Q3 μ to (μ + 3σ) Q1 to (μ + 2σ) (μ - σ) to Q3

μ to (μ + 3σ)

What is the symbol for the population standard deviation? M σ s p

σ

What is the difference between σ and s? There is no difference. σ is the standard deviation of a population whereas s is the standard deviation of a sample. σ measures where the data tend to center whereas s measures spread of data. σ is usually a known value whereas s has to be estimated from sample data.

σ is the standard deviation of a population whereas s is the standard deviation of a sample.

Which of the following is ​NOT​ one of the conditions for using the formula x̅ ± t ∗ (s/n) ? Data must be random. We must be able to compute the mean and standard deviation from sample data. σ, the standard deviation of the population, must be known. The population distribution is Normally distributed.

σ, the standard deviation of the population, must be known.