Stats Quizzes (for exam 3)

an inferential statistic to supplement null hypothesis testing

Confidence intervals are most often used as a. a descriptive statistic to supplement the calculation of the range b. a descriptive statistic to describe the likelihood of making a Type I or Type II error c. an inferential statistic to supplement calculation of correlation coefficients d. an inferential statistic to supplement null hypothesis testing

reject the null hypothesis

If the z-score for your treated sample mean is the critical region of the sampling distribution, the most appropriate statistical decision is to a. reject the null hypothesis b. reject the alternative hypothesis c. retain the null hypothesis d. retain the alternative hypothesis

the number of people of a particular age

In a frequency distribution for a person's age, the height of the bar or curved line represents a. the number of people of a particular age b. the age of the individual c. the average age of individuals d. none of the above

0.05

A 95% confidence interval is most commonly used when the alpha level is a. 0.1 b. 0.05 c. 0.01 d. 0.001

positively skewed

Reaction time is a commonly used variable in psychological research. Reaction times are usually close to the minimum possible time but sometimes take considerably longer. Distributions of reaction times are most likely: a. negatively skewed b. symmetrical c. positively skewed d. bimodal

your score was higher than most of the other student's scores

Suppose you find out that your z-score on an exam is +3.00. Which of the following is true? a. your grade was an "A" b. your score was higher than most of the other student's scores c. both A and B are correct d. none of the other options are correct

the probability of a type I error

The alpha level determines a. the probability of a type I error b. the probability of a type II error c. the critical value of the test statistic d. the effect size

all the sample means that could be obtained (for the specific sample size)

The distribution of sample means (for a specific sample size) consists of a. all the scores contained in the sample b. all the scores contained in the population c. all the sample means that could be obtained (for the specific sample size) d. the specific sample mean computed for the sample of scores

less

The larger the level of confidence, the ____ precise the interval estimate. a. more b. less c. most d. none of the options are correct

on average, how far off your sample means are likely to be from the true population mean

Conceptually, the standard error or the mean tells you a. on average, how far off your sample means are likely to be from the true population mean b. on average, how far off your scores are likely to be from the sample mean c. on average, how far off your scores are likely to be from the population mean d. that the expected value of the sample mean is equal to the population mean

with an extremely skewed distribution

Under what circumstances is the median likely to produce a better measure of central tendency than the mean? a. with an extremely skewed distribution b. with a symmetrical distribution c. when the data consists of a variable measured on a nominal scale d. when the data are numerical scores from an interval or a ratio scale

the magnitude of the difference between populations

What information can measures of effect size give us that hypothesis testing alone does not? a. the magnitude of the difference between populations b. the probability there's a difference between populations c. the true means for each population d. the true standard deviations for each population

the independent samples test uses sample means to estimate both population means

What is the main difference between an independent samples t-test and a single sample t-test? a. the independent samples test always has more scores b. the independent samples test uses sample means to estimate both population means c. the single sample test has a lower p-value d. the T is capitalized in a single-sample test

the population means are the same

What would be a reasonable null hypothesis for a two-sample t-test? a. the population means differ b. the population means are the same c. the sample means differ d. the sample means are the same

the standard error of the mean

When a random sample is selected from a population, the sample mean is not expected to be exactly equal to the population mean. On average, the size of the difference between the sample mean and the population mean is predicted by a. the standard error of the mean b. the expected value of the mean c. the mean of the population d. the standard deviation of the population

when scores are discrete

When is a bar graph more appropriate to use than a histogram? a. when scores are interval scaled b. when scores are discrete c. when scores are a ratio scale d. when scores are continuous

a 95% confidence interval from -2 to 5

Which confidence interval would lead one to NOT reject the null hypothesis that the population mean is zero (assume that the probability of a Type I error is set at 5%). a. a 95% confidence interval from -2 to 5 b. a 99% confidence interval from 2 to 5 c. a 99% confidence interval from 2 to 5 d. a 5% confidence interval from 2 to 50

the amount of time it takes to solve a problem

Which of the following is an example of a continuous variable? a. the gender of each student in a psychology class b. the number of males in each class offered by the college c. the number of children in a family d. the amount of time it takes to solve a problem

none of the other options are correct

Which of the following is true of a normal distribution? a. most individual's scores will be at the low end b. there will be an equal number of low, middle, and high scores c. most individual's scores will be at the extremes, with few scores in the middle d. none of the other options are correct

60% of the scores are above the median

Which of the following statements CANNOT be true for a distribution of scores? a. 60% of the scores are above the mean b. 60% of the scores are above the median c. 60% of the scores are above the mode d. all of the above are false statements

either a histogram or frequency polygon

You decide to create a graph with mean GPA on the y-axis and number of hours studied per week on the x-axis. Which of the following would be the most appropriate graph to use? a. bar graph b. histogram c. frequency polygon (line graph) d. either a histogram or frequency polygon

you are making a type II error

You just completed a study in which you concluded no significant difference in introversion personality scores between greek and non-greek students. It is possible that a. you are making a type II error b. you are making a type I error c. you are making both a type I and type II error d. none of the above are possible

you are making a type I error

You just completed a study in which you concluded that female students had significantly higher GPAs than male students. It is possible that a. you are making a type II error b. you are making a type I error c. you are making both a type I and a type II error d. none of the above are possible

effect size

____ allows researchers to describe (1) how far mean scores have shifted in the population of (2) the percentage of variance that can be explained by a given variable a. significance b. probability c. power d. effect size

create a bar graph that shows student average course evaluations for male and female instructors

A good example of descriptive statistics would be when you a. create a bar graph that shows student average course evaluations for male and female instructors b. concluding that male instructors receive higher course evaluations than female instructors c. creating a survey to measure course evaluations d. developing a research hypothesis regarding the role of gender in course evaluations

bar graph

A graph representing the number of majors in each department within the College of Health and Behavioral Sciences would be a a. histogram b. frequency polygon (line graph) c. bar graph d. scatterplot

an inferential technique that uses the data from a sample to draw inferences about a population

A hypothesis test is a. a descriptive technique that allows researchers to describe a sample b. a descriptive technique that allows researchers to describe a population c. an inferential technique that uses the data from a sample to draw inferences about a population d. an inferential technique that uses information about a population to make predictions about a sample

the sample size was very large

A new instructional method is found to increase average exam grades from 80.20 to 80.21. That's not much of a change, but it was found to be statistically significant. How could that happen. a. the sample size was very small b. the sample size was very large c. the population size was very small d. the population size was very large

the effect size is large, but there is little variability in the scores

A null hypothesis is most likely to be rejected when a. the effect size is small, but there is a lot of variability in the scores b. the effect size is small, but there is little variability in the scores c. the effect size is large, but there is a lot of variability in the scores d. the effect size is large, but there is little variability in the scores

the effect is likely but not certain to exist in the population

A predicted effect is tested by a null significance hypothesis test, and a statistically significant result is found. Which of the following describes the most appropriate conclusion to take from the test: a. the effect is proven to exist in the populatoin b. the e effect is proven to not exist in the population c. the effect is likely but not certain to exist in the population d. the effect is likely but not certain to not exist in the population

descriptive statistics

A researcher calculates the average reaction time (in milliseconds) for a visual stimulus and for an auditory stimulus. This is an example of a. a correlational research design b. descriptive statistics c. inferential statistics d. a parameter

a and b are correct

A researcher concludes that a new treatment works significantly better than an existing treatment for improving depression. However, this finding is just unique to the specific sample and does not reflect what would happen in the population. This is an example of a. a type I error b. incorrectly rejecting the null c. a type II error d. a and b are correct

a type I error

A researcher concludes that people who prefer dogs have significantly higher IQ's than those who prefer cats. However, this finding is just unique to the specific sample and does not reflect what would happen in the population. This is an example of a. a type II error b. a type I error c. a standard error d. none of the above are correct

there was a significant difference in test scores between the groups

A researcher conducts a study in which one group of students receives encouraging words before a test and a control group receives no encouraging words. She examines the impact of this on test scores. The results are as follows: t(40)=3.00, p=0.004. What is the most appropriate conclusion given an alpha level of 0.05? a. the group that received the encouraging words had significantly higher test scores than the control group b. there was no significant difference in test scores between those that received the encouraging words and those that did not c. there was a significant difference in test scores between the groups d. none of the other options are correct

the estimate will be less precise

A researcher increases his level of confidence from 90% to 95%. What will happen to the precision of his estimate? a. the estimate will be more precise b. the estimate will be less precise c. the precision of his estimate will not change d. it depends on the size of the population

both descriptive and inferential statistics

A statistics instructor pulls out 10 of her students' exams from a pile of 50 to start grading. Because the suspense is killing her, she calculates the mean exam score for these 10 students to get a better idea of how the whole class might do. The instructor has used a. only descriptive statistics b. only inferential statistics c. both descriptive and inferential statistics d. neither descriptive or inferential statistics

the new treatment produces results that are similar to the old treatment

A therapist is investigating the impact of a new treatment for depression compared to an old treatment. Which of the following accurately represents the null hypothesis? a. the new treatment produces different results than the old one b. the new treatment produces results that are similar to the old treatment c. the new treatment produces better results than the old treatment d. none of the other options are correct

the two samples have the same mean

A two-sample t-test results in an obtained value for t of zero. When will this happen? a. the two populations have the same mean b. the two populations have the same variance c. the two samples have the same mean d. the two samples have the same variance

falsely concluded that a treatment has an effect

A type I error means that a researcher has a. falsely concluded that a treatment has an effect b. correctly concluded that a treatment has no effect c. falsely concluded that a treatment has no effect d. correctly concluded that a treatment has an effect

falsely concluded that a treatment has no effect

A type II error means that a researcher has a. falsely concluded that a treatment has an effect b. correctly concluded that a treatment has no effect c. falsely concluded that a treatment has no effect d. correctly concluded that a treatment has an effect

above the mean by a distance equal to 2 standard deviations

A z-score of z=2.00 indicates a position in a distribution a. above the mean by 2 points b. above the mean by a distance equal to 2 standard deviations c. below the mean by 2 points d. below the mean by a distance equal to 2 standard deviations

the larger the absolute value of your test statistic, the smaller your p value

All other things being equal (e.g., sample size, etc), which of the following is true? a. the larger the absolute value of your test statistic, the smaller your p value b. the larger the absolute value of your test statistic, the larger your p value c. there is no relationship between the test statistic and the p value d. none of the other options are correct

a mean difference of 6 points and an n (sample size) of 60

All other things being equal, in which scenario would the p value for the independent samples t-test most likely be less than 0.05? a. a mean difference of 6 points and an n (sample size) of 60 b. a mean difference of 6 points and an n (sample size) of 30 c. a mean difference of 3 points and an n (sample size) of 30 d. a mean difference of 3 points and an n (sample size) of 60

the smaller the standard error of the mean

All other things being equal, the larger your sample size (n) a. the larger the standard error of the mean b. the smaller the standard error of the mean c. sample size has no impact on the standard error of the mean d. none of the other options are correct

clearer statements of causality can be made

An advantage of experimental research over correlation research is a. it is clearer to see patterns in the data b. it is easier to make predictions based on observed patterns c. the statistical methods needed are simpler d. clearer statements of causality can be made

17/44

An introductory psychology class has 9 freshman males, 15 freshman females, 8 sophomore males, and 12 sophomore females. What is the probability of randomly selecting a male from this class? a. 9/17 b. 17/17 c. 17/20 d. 17/44

all of the above are true

Any time a researcher conducts a study and uses inferential statistics, it is possible they will a. commit a type I error b. commit a type II error c. make no error in their conclusions d. all of the above are true

nominal and ordinal

Bar graphs are used to represent the frequency for which type of variables? a. only nominal b. interval and ratio c. only interval d. nominal and ordinal

small effect size

Based on the effect size conventions, d=0.18 is a a. small effect size b. medium effect size c. large effect size d. not enough information to answer this question

medium effect size

Based on the effect size conventions, d=0.60 is a a. small effect size b. medium effect size c. large effect size d. not enough information to answer this question

task performance

Dr. Spearmint conducts a study where she changes the room temperature and measures its effect on participant's performance on a simple task. What is his dependent variable? a. room temperature b. manipulation c. task performance d. room temperature's effect on task performance

a type II error

Dr. Stake concludes that morning statistics classes don't differ from afternoon classes in average grade. However, there actually is a difference at the population level. What kind of error has she made? a. a type I error b. a type II error c. a standard error d. no error has been made

25%

Each quartile of a distribution of scores contains ___ of all the scores a. 25% b. 50% c. 75% d. 100%

there is no difference between the two population means

For an independent samples t-test, the null hypothesis states that a. there is no difference between the two sample means b. there is no difference between the two population means c. one sample mean is different from the other sample mean d. one population mean is different from the other population mean

inferential method for determining whether a population parameter has a particular value

Hypothesis testing is a(n) a. descriptive method for determining the scale of measurements used b. descriptive method for estimating variability c. inferential method for determining whether a sample statistic has a particular value d. inferential method for determining whether a population parameter has a particular value

the critical region is the same size in both tests

If a researcher conducts both a one-tailed and a two-tailed hypothesis test, both with an alpha of 0.5, which is true of the two tests' critical regions? a. the one-tailed test's critical region is bigger b. the two-tailed test's critical region is bigger c. the critical region is the same size in both tests d. the size of the critical region can't be determined in either test

a false positive

If rejecting the null is thought of as a "positive" test result and failing to reject it a "negative," a type I error could also be called a. a false positive b. a false negative c. a true positive d. a true negative

a false negative

If rejecting the null is thought of as a "positive" test result and failing to reject it a "negative," a type II error could also be called a. a false positive b. a false negative c. a true positive d. a true negative

positively skewed

If the bars on a histogram are highest when scores are lowest and much less frequent for higher scores, the shape of the histogram would be: a. symmetrical b. positively skewed c. negatively skewed d. bimodal

there will be no difference in shape

If the same data is displayed in a frequency polygon (line graph) and a bar graph, how will the shapes of the two graphs differ? a. the bar graph will be more skewed b. there will be no difference in shape c. the frequency polygon will have a higher peak d. the bar graph will have a smaller range

you should reject the null hypothesis and conclude that the two group means are significantly different

If the t-value for your independent samples t-test has a p-value less than your alpha level, then a. you should retain the null hypothesis and conclude that the two group means are not significantly different b.you should reject the null hypothesis and conclude that the two group means are not significantly different c. you should reject the null hypothesis and conclude that the two group means are significantly different d. you should retain the null hypothesis and conclude that the two group means are significantly different

retain the null hypothesis

If the z-score for your treated sample mean is NOT in the critical region, then the most appropriate statistical decision is to a. retain the null hypothesis b. reject the null hypothesis c. retain the alternative hypothesis d. reject the alternative hypothesis

more sampling error

If there is greater variability of scores in your population, then you would expect a. less sampling error b. more sampling error c. variability of scores in the population is not related to sampling error d. sample means to be closer to the true population mean

sample values that are very unlikely to be obtained if the null hypothesis is true

In a hypothesis test, the critical region consists of a. sample values that are highly likely to be obtained if the null hypothesis is true b. sample values that are very unlikely to be obtained if the null hypothesis is true c. sample values that provide proof that the null hypothesis is true d. sample values that provide proof that the null hypothesis is false

the larger the range of values as estimates of the population

The higher the confidence interval (e.g., 95% vs 90%) a. the smaller the range of values as estimates of the population b. the larger the range of values as estimates of the population c. the smaller the range of values as estimates of the sample d. the larger the range of values as estimates of the sample

standard error of the mean

The measure of variability on a sampling distribution of the mean is the a. population variance b. sample variance c. sample standard deviation d. standard error of the mean

randomly assign participants to two different groups

The most powerful way to create the groups for an independent samples t-test is to a. randomly assign participants to two different groups b. repeatedly test the same group of participants twice c. match the participants in two groups on important variables d. ask participants to volunteer for one group or the other

there is no difference between the two population means

The null hypothesis for a one-sample test states a. there is no difference between the sample mean and the population mean b. there is no difference between the two population means c. there is a difference between the sample mean and the population mean d. none of the other 3 choices is correct

the difference in the two sample means observed in the study

The numerator of an independent samples t-test represents which of the following? a. the difference between the two sample standard deviations b. the standard error of the mean c. the difference between the two sample means you can expect to get by chance d. the difference in the two sample means observed in the study

probability of finding a significant effect/relationship when one in fact exists in the population

The power of a statistical test is best described as the a. probability of finding a significant effect/relationship when one in fact exists in the population b. probability of finding a type I error assuming that it exists in the population c. probability of finding a type II error assuming that it exists in the population d. the probability of missing a real effect assuming that it exists in the population

the standard deviation of the distribution of sample means

The standard error of the sample mean is a. the obtained sample mean b. the mean of the distribution of sample means c. the sample standard deviation d. the standard deviation of the distribution of sample means

the study had 34 participants and you should conclude that the two groups are NOT significantly different

The statistical output for an independent samples t-test shows t(32)=1.26, p=0.50. This output indicates that a. the study had 33 participants and you should conclude that the two groups are significantly different b. the study had 33 participants and you should conclude that the two groups are NOT significantly different c. the study had 34 participants and you should conclude that the two groups are significantly different d. the study had 34 participants and you should conclude that the two groups are NOT significantly different

none of the above

What population parameters must be known to run an independent samples t-test? a. the mean of population 1 b. the mean of population 2 c. the mean and standard deviation of population 2 d. none of the above

the two population means are different

What would be a reasonable alternative hypothesis for a two-sample t-test? a. the two population means are the same b. the two sample means are the same c. the two population means are different d. the two sample means are different

household incomes likely represent a skewed distribution

When reporting household incomes for a geographical region, the median is preferred over the mean. This is because a. the median is easier to compute b. the median is easier to interpret c. household incomes likely represent a skewed distribution d. household incomes likely represent a normal distribution

the two populations being compared probably have different means

When the null hypothesis is rejected in an independent samples t-test, what conclusion is being drawn? a. the two populations being compared probably have different means b. you've proven your hypothesis correct c. the two populations probably do not have different means d. none of the above

nominal

Whether or not someone is married represents which scale of measurement? a. nominal b. ordinal c. interval d. ratio

graduates from a psychology program by year

Which dataset would be most appropriate to use a histogram to graph? a. tests given per section of statistics b. graduates from a psychology program by year c. time taken to complete a statistics test d. psychology professors by university

the two populations have the same mean

Which of the following could be a null hypothesis of a two-tailed hypothesis test? a. the two populations have the same mean b. the two populations have different means c. population 1's mean is greater than or equal to population 2's mean d. population 1's mean is less than population 2's mean

the standard error of the mean

Which of the following defines the expected difference between a population's mean and the mean of a sample randomly drawn from it? a. the population mean b. the population variance c. the standard deviation d. the standard error of the mean

they provide a range of estimated values for the population mean rather than a single number

Which of the following describes why confidence intervals are often useful? a. they tell us the standard deviation of the population b. they change the probability of receiving a significant result c. they decrease the power of the design d. they provide a range of estimated values for the population mean rather than a single number

z-scores change ordinal scales to ratio scales

Which of the following is NOT a reason why being able to calculate z-scores is considered important? a. z-scores standardize where scores fall relative to the mean b. z-scores change ordinal scales to ratio scales c. z-scores allow scores from different variables or datasets to be directly compared d. z-scores allow specific estimates of relative standing in a population even when information is limited

weight

Which of the following is a continuous variable? a. weight b. placement in a race c. number of traffic tickets received in a year d. college major

alpha level determines whether you are conducting a 1-tailed or 2-tailed test

Which of the following statements about the alpha level of a hypothesis test is NOT true? a. alpha level determines the size of the region of rejection (critical region) b. alpha level determines whether you are conducting a 1-tailed or 2-tailed test c. alpha level determines the maximum p-value that will allow the researcher to reject the null hypothesis d. alpha level is usually set at .05 or .01

you randomly assign children with a diagnosis of ADHD to two different treatment groups and then compare the two groups on their academic success in class for a month

Which of the following studies would best be analyzed with an independent samples t-test? a. you select a group of children diagnosed with ADHD and assess their academic success in class, first with on treatment for a mont, then with a second treatment for a month, and then with a third treatment for a month b. you randomly assign children with a diagnosis of ADHD to three different treatment groups and then compare the three groups on their academic success in class for one month c. you select a group of children diagnosed with ADHD and assess their academic success in class, first with one treatment for a month and then again with a second treatment for a month d. you randomly assign children with a diagnosis of ADHD to two different treatment groups and then compare the two groups on their academic success in class for a month

it shows the probability that you would have obtained the sample statistic's value or more extreme if the null were true

Which of these is the correct interpretation of the p value? a. it shows the probability that you would have obtained the sample statistic's value or more extreme if the null were not true b. it shows the probability that you would have obtained the sample statistic's value or more extreme if the null were true c. if it is large, it means there is a statistical significance d. none of the other options are correct