BNAD Test 3

The two pieces of information that are necessary to determine the value of t(df) are

-level of significance -the sample lie or degrees of freedom

A confidence interval narrows if the following is accomplished...

-the chosen confidence level decreases -the sample size increases

A 95% confidence interval for the population mean is constructed as 6+/-2. What is the probability of error, a?

.05

For a 95% confidence interval the population mean, if samples of size n are drawn repeatedly from a given population then...

5% of the sample means will fall outside of the corresponding confidence interval

Which of the following variables is ratio? A. Gender B. Temperature (Fahrenheit) C. Time until the next election D. Religious affiliation

C. Time until the next election

The central limit theorem states that, for any distribution, as n gets larger, the shape of the sampling distribution of the sample mean _______. A. becomes larger B. becomes smaller C. is closer to a normal distribution D. is closer to the standard deviation

C. is closer to a normal distribution

Compared to the standard deviation of the population, the standard error of the mean (especially for large samples) will be: a. larger b. smaller c. equal d. not enough information is known

b. smaller

Albert compared the race times of 20 male and female jockeys for race horses. He wanted to know who averaged faster rides. Which of the following is best describes this study? a. correlation b. t-test c. one-way ANOVA d. two-way ANOVA

b. t-test

Albert compared the race times of 20 male and female jockeys for race horses (two samples). He is comparing these two mean and does not know the standard deviation for the population. Which of the following is best describes this study? a. correlation b. one-sample t-test c. two-sample t-test d. one-sample z-test

c. two-sample t-test

A survey was conducted to see whether men or women superintendents make more money. A Type I error would be a. claiming men make more money, when they don't b. claiming women make more money, when they don't c. claiming no difference between amount of money made, when there is a difference d. claiming there is a difference between the amount of money made, when there is no difference

d. claiming there is a difference between the amount of money made, when there is no difference

Ian was interested in the effect of incentives and age for girl scouts on the number of cookies sold. He randomly assigned girl scouts into one of three groups. The three groups were given one of three incentives and he looked to see who sold more cookies. The 3 incentives were: 1) Trip to Hawaii, 2) New Bike or 3) Nothing. He also measured their age. This is an example of a ___. a. quasi-experiment b. true experiment c. correlational study d. mixed design

d. mixed design

Each t distribution is identified by its....

degrees of freedom

A particular value of an estimator is called a/an...

estimate

When a sample statistic is used to make inferences about a population parameter, is it referred to as a/an...

estimator

If X is normally distributed with expected value u and standard deviation o, then x is normally distributed with...

expected value u and standard deviation of square root n

A 95% confidence interval for the population mean implies that....

for repeated samples, 95% of the sample means will fall within the interval

A t distribution...

has slightly broader tails than the z distribution

What is a primary requirement for a "good" sample?

it is representative of the population we are trying to describe

A sample statistic is considered biased if...

it systematically over-or under estimates the unknown parameter being estimated

In order to construct a confidence interval for u, the sampling distribution of the estimator x must follow or approximately follow a _______- distribution

normal

The estimator x follows a normal distribution when the underlying population follows a _____ distribution

normal

When the sample size is sufficiently large we can approximate the sampling distribution of the sample proportion using the...

normal distribution

In order to derive a confidence interval for u, the estimator x must have a...

normal sampling distribution

The parameter ____ represents the proportion of successes in a population and the statistic_____ represents the proportion successes in a sample

p, P

When estimating the population mean, the t(dt) distribution is used when the...

population variance is unknown

Which of the following is a descriptive measure for a qualitative variable?

proportion

The probability distribution of the sample mean is commonly referred to as the

sampling distribution of x

The probability distribution of the sample mean is commonly referred to as the ____

sampling distribution of x

The most practical way to reduce the margin of error is by...

selecting a larger sample size

What kind of sampling is more likely to be used by political pollsters who want to ensure that each religious group is represented in the sample?

stratified random sampling

in _____, the population is divided up into mutually exclusive and collectively exhaustive groups called strata. the sample consists of elements from each stratum...

stratified random sampling

The standard error of the sample mean is NOT affected by..

the confidence level affects the margin of error but not the standard

the expected value of x is equal to _____

u

When the confidence level increases from 95% to 99% the confidence interval for the population mean_____

widens

Albert compared the race times of 20 male and female jockeys for race horses. He wanted to know who averaged faster rides. Which of the following is true?

a. The null hypothesis is that there is no difference in race times between the genders b. The null hypothesis is that there is a difference between the genders

Albert compared the race times of 20 male and female jockeys for race horses. He wanted to know who averaged faster rides. He concluded p < 0.05 what does this mean? a. There is a significant difference between the means b. There is no significant difference between the means

a. There is a significant difference between the means

Elaina was interested in the relationship between the grade point average and starting salary. She recorded for GPA. and starting salary for 100 students and looked to see if there was a relationship. This is an example of a _____. a. correlation b. t-test c. one-way ANOVA d. two-way ANOVA

a. correlation

Type I errors are sometimes called ____; while Type II errors are sometimes called ____. a. false alarms; misses b. misses; false alarms c. standard errors of the mean; standard errors of the prediction d. standard errors of the prediction; standard errors of the mean

a. false alarms; misses

A survey was conducted to see whether women superintendents make more money than men. This is a a. one-tailed test b. two-tailed test c. three-tailed test d. not enough information

a. one-tailed test

Which of the following represents a significant finding: a. p < 0.05 b. the observed statistic (z score) is not bigger than critical value c. the observed z statistic is nearly zero d. do not reject the null hypothesis

a. p < 0.05

A survey was conducted to see whether men or women superintendents make more money. This is a a. quasi, between subject design b. quasi, within subject design c. true, between subject design d. true, within subject design

a. quasi, between subject design

Suppose you are constructing a confidence interval for the population mean. For a given confidence level and sample size, the width of the interval is wider for a ....

larger standard deviation

When constructing a confidence interval for the population mean when the population standard deviation is unknown the degrees of freedom for the t distribution are defined as

n-1

If the shape of the population from which a simple random sample is drawn is normal, then the shape of the sampling distribution of x is...

normal

A population consists of all items of interest in a statistical problem, whereas a ______ is a subset of the population

sample

Suppose you are constructing interval for the population mean. For a given confidence level and standard deviation, the width of the interval is wider for a...

smaller sample size

What is a characteristic of a "bad" sample?

the sample is not representative of the population we are trying to describe

Howdy the t(df) and z distributions differ?

the t(df) distribution has broader tails (it is flatter around zero)

Selection bias occurs when...

there is a systematic exclusion of certain groups from consideration for the sample

Nonresponse bias occurs when...

those responding to a survey or poll differ systematically from the non-respondents

Stratified sampling is preferred to cluster sampling when the objective is...

to increase precision

T/F: a 95% confidence interval for u implies that if numerous samples are taken from a population, 95% of the intervals will contain u

true

T/F: for a given sample size n and population standard deviation o, the lower the confidence level 100(1-a)% the narrower the confident interval

true

T/F: if we had access to data that included the entire population then the values of the parameters would be known and no statistical inference would be required

true

What is the most typical form of a calculated confidence interval? A. Point estimate ± Standard error B. Point estimate ± Margin of error C. Population parameter ± Standard error D. Population parameter ± Margin of error

B. Point estimate ± Margin of error

The central limit theorem states that, for any distribution, as n gets larger, the variability of the sampling distribution of the sample mean _______. A. becomes larger B. becomes smaller C. is closer to a normal distribution D. is closer to the standard deviation

B. becomes smaller

Standard deviation formula

Square root of variance

A sample is...

a subset of a population

Albert compared the race times of 20 male and female jockeys for race horses. He wanted to know who averaged faster rides. Which of the following is true? a. The IV is gender while the DV is time to finish a race b. The IV is time to finish a race while the DV is gender

a. The IV is gender while the DV is time to finish a race

Albert compared the race times of 20 male and female jockeys for race horses. He wanted to know who averaged faster rides. Which of the following is true? a. This is a quasi, between participant design b. This is a quasi, within participant design c. This is a true, between participant design d. This is a true, within participant design

a. This is a quasi, between participant design

A survey was conducted to see whether men or women superintendents make more money. The independent variable is a. nominal level of measurement b. ordinal level of measurement c. interval level of measurement d. ratio level of measurement

a. nominal level of measurement

A survey was conducted to see whether men or women superintendents make more money. This is a a. one-tailed test b. two-tailed test c. three-tailed test d. not enough information

b. two-tailed test

Victoria was also interested in the effect of vacation time on productivity of the workers in her department. In her department some workers took vacations and some did not. She measured the productivity of those workers who did not take vacations and the productivity of those workers who did (after they returned from their vacations). This is an example of a _____. a. quasi-experiment b. true experiment c. correlational study

a. quasi-experiment

Albert compared the heights of a small sample of 10 women from the women's gymnastics team to the mean for the whole team (population). This is an example of a one-sample t-test. He found an observed t(9) = .04, what should he do? a. Reject the null hypothesis b. Do not reject the null hypothesis c. There is not enough information

b. Do not reject the null hypothesis

If Alberta reported that t(198) = 2.38; p < 0.05 when he compared the race times of equal numbers of male and female jockeys for race horses. We know that a. She had 100 female jockeys and 100 male jockeys and there was no significant difference between the two groups b. She had 100 female jockeys and 100 male jockeys and there was a significant difference between the two groups c. 99 female jockeys and 99 male jockeys and there was no significant difference between the two groups d. 99 female jockeys and 99 male jockeys and there was no significant difference between the two groups

b. She had 100 female jockeys and 100 male jockeys and there was a significant difference between the two groups

Albert compared the race times of 20 male and female jockeys for race horses. He wanted to know who averaged faster rides. A Type I Error would claim that: a. There is a difference when in fact there is b. There is a difference when in fact there isn't one c. There is no difference when in fact there isn't one d. There is no difference when in fact there is a difference

b. There is a difference when in fact there isn't one

Albert compared the race times of 20 male and female jockeys for race horses. He wanted to know who averaged faster rides. Which of the following is true? a. This is a one-tailed test b. This is a two-tailed test

b. This is a two-tailed test

A survey was conducted to see whether men or women superintendents make more money. The dependent variable is a. continuous and qualitative b. continuous and quantitative c. discrete and qualitative d. discrete and quantitative

b. continuous and quantitative

A survey was conducted to see whether women superintendents make more money than men. A t-test was conducted, which of the following best describes the results: Note the results were in the unpredicted direction a. reject the null b. do not reject the null c. not enough information

b. do not reject the null

Marietta is a manager of a movie theater. She wanted to know whether there is a difference in concession sales for afternoon (matinee) movies vs. evening movies. She took a random sample of 25 purchases from the matinee movie (mean of $7.50) and 25 purchases from the evening show (mean of $10.50). She compared these two means. This is an example of a _____. a. correlation b. t-test c. one-way ANOVA d. two-way ANOVA

b. t-test

Pharmaceutical firm tested whether fish-oil capsules taken daily decrease cholesterol. They measured cholesterol levels for 30 male subjects and then had them take the fish-oil daily for 2 months and tested their cholesterol levels again. Then they compared the mean cholesterol before and after taking the capsules. This is an example of a _____. a. correlation b. t-test c. one-way ANOVA d. two-way ANOVA

b. t-test

Ian was interested in the effect of incentives for girl scouts on the number of cookies sold. He randomly assigned girl scouts into one of three groups. The three groups were given one of three incentives and he looked to see who sold more cookies. The 3 incentives were: 1) Trip to Hawaii, 2) New Bike or 3) Nothing. This is an example of a ___. a. quasi-experiment b. true experiment c. correlational study

b. true experiment

A t-test was conducted to see whether "Bankers" or "Retailers" spend more time in front of their computer. Which critical t would be the best to use a. 3.5 b. 1.859 c. 2.306 d. .004 e. .008

c. 2.306

A t-test was conducted to see whether "Bankers" or "Retailers" spend more time in front of their computer. How many bankers and retailers were measured a. 10 bankers were measured; 8 retailers were measured b. 10 bankers were measured; 10 retailers were measured c. 5 bankers were measured; 5 retailers were measured

c. 5 bankers were measured; 5 retailers were measured

Which of the following would represent a one-tailed test? a. Please test to see whether men or women are taller b. With an alpha of .05 test whether advertising increases sales c. With an alpha of .01 test whether management strategies affect worker productivity d. Does a stock trader's education affect the amount of money they make in a year

c. With an alpha of .01 test whether management strategies affect worker productivity

A survey was conducted to see whether men or women superintendents make more money. A Type II error would be a. claiming men make more money, when they don't b. claiming women make more money, when they don't c. claiming no difference between amount of money made, when there is a difference d. claiming there is a difference between the amount of money made, when there is no difference

c. claiming no difference between amount of money made, when there is a difference

A survey was conducted to see whether men or women superintendents make more money. A Type II error would be a. claiming men make more money, when they don't b. claiming women make more money, when they don't claiming no difference between amount of money made, when there is a difference d. claiming there is a difference between the amount of money made, when there is no difference

c. claiming no difference between amount of money made, when there is a difference

Mark and Melvin work inside Intel's semiconductor fabrication plants. In these "clean rooms" the workers wear "bunny suits". Mark and Melvin are each assigned a different team to measure the workers. Both teams measure the same sample of 100 workers and determine the very specific dimensions of their "bunny suits". Mark spends a week training his team of data collectors, providing identical tape measures and creating a strict protocol for measuring the workers. Melvin however, simply sends out his team to measure the workers, with little instruction, and consequently Melvin's workers make many more mistakes in recording the data, and the data are more variable. How would you explain the difference in variability between the two groups? The difference in variability between these two group is due to: a. the difference in sample size, because as sample size increases variability decreases b. differences in the population, because if the population is more variable, the sample will be more variable c. differences in the amount of random error in the two samples, because as random error increases so will variability d. all of the above are reasons why Melvin's data are more variable than Mark's

c. differences in the amount of random error in the two samples, because as random error increases so will variability

A survey was conducted to see whether men or women superintendents make more money. The null hypothesis is a. men make more money b. women make more money c. no difference between amount of money made d. there is a difference between the amount of money made

c. no difference between amount of money made

An advertising firm wanted to know whether the size of an ad in the margin of a website affected sales. They compared 4 ad sizes (tiny, small, medium and large). They posted the ads and measured sales. This is an example of a _____. a. correlation b. t-test c. one-way ANOVA d. two-way ANOVA

c. one-way ANOVA

Agnes compared the heights of the women's gymnastics team and the women's basketball team. If she doubled the number of players measured (but ended up with the same means) what effect would that have on the results? a. the means are the same, so the t-test would yield the same results. b. the means are the same, but the variability would increase so it would be harder to reject the null hypothesis. c. the means are the same, but the variability would decrease so it would be easier to reject the null hypothesis

c. the means are the same, but the variability would decrease so it would be easier to reject the null hypothesis

Agnes was interested in the grade point averages (GPA) of different student athletes from different sports. She compared the GPAs of softball players, and swimmers. In her initial study she measured 10 athletes from each sport. She then wanted to expand her study, and measured 200 athletes from each sport. It turns out that while the means stayed the same, her results were different. Which is the most likely effect of this dramatic increase in sample size (from 10 per group to 200 per group?). Even though the means were the same a. the variability increased so it was easier to reject the null b. the variability increased so it was harder to reject the null c. the variability decreased so it was easier to reject the null d. the variability decreased so it was harder to reject the null

c. the variability decreased so it was easier to reject the null

A theorem that allows us to use the normal probability distribution to approximate the sampling distribution of the sample mean whenever the sample size is large is known as the ....

central limit theorem

The central limit theorem states that, for any distribution, as n gets larger, the sampling distribution of the sample mean becomes

closer to a normal distribution

When examining the possible outcome of an election what type of confidence interval is most suitable for estimating the current support for a candidate?

confidence interval for the population proportion

A survey was conducted to see whether men or women superintendents make more money. The dependent variable is a. nominal level of measurement b. ordinal level of measurement c. interval level of measurement d. ratio level of measurement

d. ratio level of measurement

How do we decide whether to use a z test or a t-test? a. t scores are only used when inferences are made about other samples. b. t scores are used when a study is analyzed with a population mean. c. t scores are used only when the sample size is greater than 30. d. t scores are used when the population standard deviation is unknown

d. t scores are used when the population standard deviation is unknown

Agnes compared the heights of the women's gymnastics team and the women's basketball team. If she doubled the number of players measured (but ended up with the same means) what effect would that have on the results? a. the variance would get bigger and the confidence interval would get wider b. the variance would get bigger and the confidence interval would get narrower c. the variance would get smaller and the confidence interval would get wider d. the variance would get smaller and the confidence interval would get narrower

d. the variance would get smaller and the confidence interval would get narrower

A survey was conducted to see whether men or women superintendents make more money. If the null hypothesis was rejected we will conclude that a. men make more money b. women make more money c. no difference between amount of money made d. there is a difference between the amount of money made

d. there is a difference between the amount of money made

A survey was conducted to see whether men or women superintendents make more money. If the null hypothesis was rejected we will conclude that a. men make more money b. women make more money no difference between amount of money made d. there is a difference between the amount of money made

d. there is a difference between the amount of money made

Suppose you are constructing a confidence interval for the population mean. For a given sample size and standard deviation, the width of the interval is wider, for a >>>>

higher confidence level increases the margin of error. increasing the margin of error leads to a wider interval

The sample size required to approximate the normal distribution depends on...

how much the population varies from normality

The expected value of x is equal to the ______

population mean

The parameter p represents the...

population portion

A population has a mean of 50 and a standard deviation of 10. A random sample of 144 is selected. The expected value of x is equal to...

the expected value of x is equal to u=50

If we were to sample repeatedly from a given population, the average value of the sample means will equal...

the population mean