My EPPP - EPPP Practice Questions: Statistics and Research Design
In a positively skewed distribution, the mean gets pulled up by the high outliers (long right tail), while the mode stays where the peak As long as your sample size is large enough, the sampling distribution of the mean will approximate a normal distribution, even if the original population isn’t normal.
In a positively skewed distribution, from smallest to largest in magnitude, the measures of central tendency are:
a. mean, median, mode.
b. mean, mode, median.
c. mode, median, mean.
d. mode, mean, median.
c. mode, median, mean.
Remembering that the “tail tells the tale” and that the median is always the middle score would have helped you identify the correct answer to this question: In a positively skewed distribution, the mode has the smallest value, the median has the middle value, and the mean (which is affected most by the extreme scores in the positive tail) has the largest value.
Key Terms
In a positively skewed distribution, from smallest to largest in magnitude, the measures of central tendency are:
a. mean, median, mode.
b. mean, mode, median.
c. mode, median, mean.
d. mode, mean, median.
c. mode, median, mean.
Remembering that the “tail tells the tale” and that the median is always the middle score would have helped you identi...
The Central Limit Theorem predicts that a sampling distribution of the mean will increasingly approach a normal shape:
a. regardless of the shape of the population distribution as the sample size increases.
b. regardless of the shape of the population distribution as the number of samples increases.
c. only when the population distribution does not deviate from the normal.
d. only when the sample distributions do not deviate significantly from the normal.
a. regardless of the shape of the population distribution as the sample size increases
This is the correct description of the prediction of t...
The probability of making a Type I error is increased by:
a. conducting a single multivariate test rather than several univariate tests.
b. changing the level of significance from .01 to .05.
c. changing beta from .
01 to .05.
d. conducting a two-tailed (rather than a one-tailed) test.
b. changing the level of significance from .01 to .05
The probability of making a Type I error is directly affected by the level of significanc...
“Sampling error” is due to:
a. the unreliability of the test.
b. the invalidity of the test.
c. random factors that produce a nonrepresentative sample.
d. non-random factors that produce a nonrepresentative sample.
c. random factors that produce a nonrepresentative sample
As the result of random (chance) factors, the sample may not “mirror” the populatio...
To increase power, you would:
a. reduce alpha.
b. increase beta.
c. reduce sample size.
d. increase sample size.
d. increase sample size
Increasing sample size makes it easier to statistically detect the effects of the independent variable; i.e., it incr...
To calculate the F-ratio for a one-way ANOVA:
a. MSB is multiplied by MSW.
b. MSB is divided by MSW.
c. MSW is divided by MSB.
d. MSW is subtracted from MSB.
b. MSB is divided by MSW.
The F-ratio is calculated by dividing a measure of treatment plus error by a measure of error only in order to obta...
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| Term | Definition |
|---|---|
In a positively skewed distribution, from smallest to largest in magnitude, the measures of central tendency are: a. mean, median, mode. b. mean, mode, median. c. mode, median, mean. d. mode, mean, median. | c. mode, median, mean. Remembering that the “tail tells the tale” and that the median is always the middle score would have helped you identify the correct answer to this question: In a positively skewed distribution, the mode has the smallest value, the median has the middle value, and the mean (which is affected most by the extreme scores in the positive tail) has the largest value. |
The Central Limit Theorem predicts that a sampling distribution of the mean will increasingly approach a normal shape: a. regardless of the shape of the population distribution as the sample size increases. b. regardless of the shape of the population distribution as the number of samples increases. c. only when the population distribution does not deviate from the normal. d. only when the sample distributions do not deviate significantly from the normal. | a. regardless of the shape of the population distribution as the sample size increases This is the correct description of the prediction of the Central Limit Theorem. Note that it is the size of the sample that is the critical factor. (The Central Limit Theorem always assumes an infinite number of samples.) |
The probability of making a Type I error is increased by: a. conducting a single multivariate test rather than several univariate tests. b. changing the level of significance from .01 to .05. c. changing beta from . 01 to .05. d. conducting a two-tailed (rather than a one-tailed) test. | b. changing the level of significance from .01 to .05 |
“Sampling error” is due to: a. the unreliability of the test. b. the invalidity of the test. c. random factors that produce a nonrepresentative sample. d. non-random factors that produce a nonrepresentative sample. | c. random factors that produce a nonrepresentative sample As the result of random (chance) factors, the sample may not “mirror” the population in important characteristics. This is referred to as sampling error. |
To increase power, you would: a. reduce alpha. b. increase beta. c. reduce sample size. d. increase sample size. | d. increase sample size Increasing sample size makes it easier to statistically detect the effects of the independent variable; i.e., it increases power. Other ways to increase power include increasing the magnitude of alpha, using a reliable dependent variable measure, and using a parametric statistical test. |
To calculate the F-ratio for a one-way ANOVA: a. MSB is multiplied by MSW. b. MSB is divided by MSW. c. MSW is divided by MSB. d. MSW is subtracted from MSB. | b. MSB is divided by MSW. The F-ratio is calculated by dividing a measure of treatment plus error by a measure of error only in order to obtain an estimate of treatment effects. MSB (mean square between) is a measure of treatment plus error, while MSW (mean square within) is a measure of error only, and the F-ratio is calculated by dividing MSB by MSW. |
For her math class assignment, a high school student will compare the average number of hours that students in her school spend playing computer games each day to the national average. To analyze the data she collects, the student will use which of the following statistical tests? a. single-sample t-test b. independent samples t-test c. single-sample chi-square test d. multiple-sample chi-square test | a. single-sample t-test The t-test is used to compare two means, and when one of the means is a sample mean and the other is a known population mean, the appropriate t-test is the single-sample t-test. |
An investigator wants to test the hypothesis that the average number of aggressive acts that children exhibit in an unfamiliar situation is related to gender and sociability (“sociable” or “shy”). He obtains a sample of 30 boys and 30 girls who have been rated as either sociable or shy and then has observers count the number of aggressive acts each child exhibits in an unfamiliar situation during a 30-minute play period. The best statistical test to analyze the data the investigator collects in this study is which of the following? a. t-test for independent samples b. chi-square test c. one-way ANOVA d. two-way ANOVA | d. two-way ANOVA The research study involves two independent variables (sociability and gender) and a single dependent variable that is measured on a ratio scale (number of aggressive acts). The appropriate statistical test is the two-way analysis of variance. |
A researcher uses a factorial ANOVA to statistically analyze the effects of four types of training strategies and three levels of self-efficacy on a measure of job performance. The results indicate that there are significant main effects of each independent variable and a significant interaction. The researcher will conclude that: a. training is effective regardless of level of self-efficacy. b. each type of training is equally effective for each level of self-efficacy. c. the most effective type of training depends on level of self-efficacy. d. overall, training is effective only for people with a certain level of self-efficacy. | c. the most effective type of training depends on level of self-efficacy Because the interaction is significant, this means that the effects of the types of training may differ for different levels of self-efficacy – e.g., training method #1 might be most effective for people with low self-efficacy, while training method #2 might be most effective for people with high self-efficacy. |
Which of the following provides a measure of shared variability and is calculated by squaring the correlation coefficient? a. coefficient of concordance b. kappa statistic c. coefficient of determination d. eta | c. coefficient of determination The coefficient of determination is calculated by squaring the correlation coefficient (r) and provides a measure of shared variability, or the amount of variability in one variable that is explained by variability in another variable |
Which of the following correlation coefficients is useful for determining the degree of association between two nominal variables? a. biserial b. contingency c. Spearman d. Pearson | b. contingency The contingency coefficient is used to determine the correlation between two nominal (categorical) variables – for example, between a parent’s parenting style (authoritative, authoritarian, permissive, or rejecting/neglecting) and his/her educational achievement (high school graduate, undergraduate degree, master’s degree, doctoral degree). |
An organizational psychologist is hired by a company to help identify job applicants who should be considered for managerial level positions. In this situation, the psychologist wants to develop a selection test battery that will provide the following information: “Which group (manager or non-manager) does a job applicant most closely resemble?” Which of the following methods for combining selection test scores will be most useful for answering this question? a. multiple regression b. discriminant function analysis c. factor analysis d. canonical correlation | b. discriminant function analysis There are several methods for combining predictor scores to estimate performance on a criterion. When the criterion is group membership (i.e., when the criterion is measured on a nominal scale), discriminant function analysis is an appropriate method. |
External validity is likely to be a problem when: a. the results of a research study indicate that a test’s validity coefficient differs for members of different groups. b. an investigator uses a nonparametric statistical test to analyze the data she collected in a research study. c. the research study conducted by an investigator does not include a no-treatment control (comparison) group. d. the research design used by an investigator involves sequentially administering the different levels of the IV to the same group of participants. | d. the research design used by an investigator involves sequentially administering the different levels of the IV to the same group of participants External validity refers to the generalizability of research results to different participants, settings, and conditions. This external validity of the research study described in this answer is threatened by multiple treatment interference because it involves exposing all participants different levels of the IV. Consequently, it will not be possible to generalize the results to situations in which individuals receive only one level of the IV. |
When using an ABAB design, you are: a. administering two different treatments at two different times. b. administering one treatment at two different times. c. administering one treatment to two different groups. d. administering one treatment to two different behaviors. | b. administering one treatment at two different times The ABAB design has two no treatment (A) phases and two treatment (B) phases. The same treatment is administered during the B phases. |