Exam 3 Psych Stats Part 2

For an experiment comparing two treatment conditions, an independent-measures design would obtain ________ score(s) for each subject and a repeated-measures design would obtain ________ score(s) for each subject. a. 1, 2 b. 2, 1 c. 1, 1 d. 2, 2

a. 1, 2

A researcher conducts a research study comparing two treatment conditions and obtains 20 scores in each treatment. If the researcher used a repeated-measures design, then how many individuals participated in the research study? a. 20 b. 21 c. 40 d. 10

a. 20

For a repeated-measures study with a sample of n = 25 participants, a researcher obtains MD = 6 with a variance of s2 = 8 for the difference scores. If the researcher uses a confidence interval to estimate the size of the treatment effect, what value will be in the center of the interval? a. 6 b. 8 c. 0 d. Impossible to determine without knowing the percentage of confidence.

a. 6

If a repeated-measures study shows a significant difference between two treatments with α = .01, then you can be sure that ________. a. A significant effect does not necessarily mean that the effect size will be large. b. both Cohen's d and r2 are large c. the value of Cohen's d is large d. the percentage of variance explained (r2) is large

a. A significant effect does not necessarily mean that the effect size will

The repeated-measures t statistic uses the mean (MD) and the SS from one sample of difference scores to test a hypothesis about one population of difference scores. If each sample has n = 10 scores, then which of the following samples will produce the largest value for the t statistic? a. MD = 10 with SS = 20 b. MD = 5 with SS = 40 c. MD = 10 with SS = 40 d. MD = 5 with SS = 20

a. MD = 10 with SS = 20

The data from a repeated-measures research study show that the difference between treatment I and treatment II is large and positive for some subjects, large and negative for some subjects, and near zero for some subjects. The sample of difference scores will produce a. a large sample variance and a small t statistic. b. a large sample variance and a large t statistic. c. a small sample variance and a large t statistic. d. a small sample variance and a small t statistic.

a. a large sample variance and a small t statistic.

A researcher conducts an experiment comparing two treatment conditions and obtains 20 scores in each treatment. Which design would require the smallest number of participants? a. a repeated-measures design b. an independent-measures design c. Independent- and repeated-measures designs both use a total of 20 participants.

a. a repeated-measures design

A group of participants is measured before and after a treatment in a repeated-measures study. If the treatment has a consistent effect on all of the participants, then the difference scores should show ________. a. a small variance b. a large mean difference c. a large variance d. a small mean difference

a. a small variance

A repeated-measures experiment and a matched-subjects experiment both produce t statistics with df = 20. Which experiment used more subjects? a. matched subjects b. repeated measures c. They both used n = 20 subjects. d. They both used n = 40 subjects.

a. matched subjects

A research report describing the results from a repeated-measures study states, "The data showed a significant difference between treatments, t(22) = 4.71, p < .01." From this report you can conclude that the outcome of the hypothesis test was ________. a. to reject the null hypothesis b. to make a Type II error c. to make a Type I error d. to fail to reject the null hypothesis

a. to reject the null hypothesis

The repeated-measures t statistic uses the mean (MD) and the SS from one sample of difference scores to test a hypothesis about one population of difference scores. The t statistic has exactly the same structure as the single-sample t statistic presented in Chapter 9. If a researcher obtains a mean of MD = 3 with SS = 48 for a sample of n = 4 difference scores, then what is the value for the repeated-measures t? a. 3 b. 3/2 = 1.50 c. 3/16 = 0.19 d. 3/4 = 0.75

b. 3/2 = 1.50

A repeated-measures design uses one group of participants with each individual measured in two conditions or at two different times. The difference between the two scores is found for each individual and the sample of difference score is used to test a hypothesis about the population of difference scores. The following data were obtained from a repeated-measures research study. What is the value of the sample mean difference for these data? a. 5 b. 4 c. 20 d. 4.6

b. 4

A repeated-measures design uses one group of participants with each individual measured in two conditions or at two different times. A repeated-measures study would not be appropriate for which of the following situations? a. The effect of a treatment is studied in a small group of individuals with a rare disease. b. A researcher would like to compare individuals from two different populations. c. A researcher would like to study the effect of practice on performance. d. A developmental psychologist examines how behavior unfolds by observing the same group of children at different ages.

b. A researcher would like to compare individuals from two different populations.

A researcher conducts a repeated-measures study comparing two treatment conditions with a sample of n = 25 participants and obtains a t statistic of t = 2.21. Which of the following is the correct decision for a two-tailed test? a. Reject the null hypothesis with either α = .05 or α = .01. b. Reject the null hypothesis with α = .05 but fail to reject with α = .01. c. Cannot determine the correct decision without more information d. Fail to reject the null hypothesis with either α = .05 or α = .01.

b. Reject the null hypothesis with α = .05 but fail to reject with α = .01.

In general, what characteristics of the data (difference scores) are most likely to produce a significant t statistic for the repeated-measures hypothesis test? a. a large mean difference and large variance b. a large mean difference and small variance c. a small mean difference and small variance d. a small mean difference and large variance

b. a large mean difference and small variance

A researcher plans to conduct a research study comparing two treatment conditions with a total of 20 scores in each treatment. Which of the following designs would require the smallest number of subjects? a. an independent-measures design b. a repeated-measures design c. a matched-subjects design d. all of the above would require the same number of subjects

b. a repeated-measures design

A repeated-measures design uses one group of participants with each individual measured in two conditions or at two different times. For which of the following situations would a repeated-measures research design be appropriate? a. comparing verbal skills for girls versus boys at age 3 b. comparing pain tolerance before and after taking a new pain medication c. comparing self-esteem for students who participate in school athletics versus those who do not d. comparing problem solving skills for science majors versus art majors at a college

b. comparing pain tolerance before and after taking a new pain medication

As the variance of the difference scores increases, the likelihood of rejecting the null hypothesis ________ and measures of effect size such as r2 or Cohen's d ________. a. increase, decrease b. decrease, decrease c. increase, increase d. decrease, increase

b. decrease, decrease

An advantage of a repeated-measured design (compared to an independent-measures design) is that it reduces the contribution of error variability due to ________. a. the effect of the treatment b. individual differences c. degrees of freedom d. MD

b. individual differences

For which of the following situations would a repeated-measures design have the maximum advantage over an independent-measures design? a. when very few subjects are available and individual differences are small b. when very few subjects are available and individual differences are large c. when many subjects are available and individual differences are small d. when many subjects are available and individual differences are large

b. when very few subjects are available and individual differences are large

If the null hypothesis is true, on average the expected value for the related samples t statistic is ________. a. t > 1.96 b. 1.96 c. 0 d. 1

c. 0

What is the value of the estimated standard error for the following set of D scores? 4, 8, 4, 4 a. 12 b. 4 c. 1 d. 2

c. 1

A research report describing the results from a repeated-measures study includes the following: "The data show no significant difference between the two treatments, t(10) = 1.65, p > .05." Based on this report, you can conclude that a total of ________ individuals participated in the research study . a. 10 b. 12 c. 11 d. 9

c. 11

The repeated-measures t statistic uses the mean (MD) and the SS from one sample of difference scores to test a hypothesis about one population of difference scores. The t statistic has exactly the same structure as the single-sample t statistic presented in Chapter 9. If a researcher obtains a mean of M = 5 with SS = 288 for a sample of n = 9 difference scores, then what is the estimated standard error for the sample mean difference? a. 36 b. 4 c. 2 d. 16

c. 2

Which of the following tends to occur when sample size is increased? a. The variance of the difference scores decreases. b. The sample mean difference decreases. c. All of the other options occur when sample size is increased. d. The standard error of the mean difference decreases.

c. All of the other options occur when sample size is increased.

A researcher conducts a repeated-measures study comparing two treatment conditions with a sample of n = 10 participants and obtains a t statistic of t = 2.01. Which of the following is the correct decision about the null hypothesis? a. Cannot determine the correct decision without more information b. Reject the null hypothesis with α = .05 but fail to reject with α = .01. c. Fail to reject the null hypothesis with either α = .05 or α = .01. d. Reject the null hypothesis with either α = .05 or α = .01.

c. Fail to reject the null hypothesis with either α = .05 or α = .01.

Which of the following would have little or no influence on effect size as measured by Cohen's d or by r2? a. All of the other three options would influence the magnitude of effect size. b. Increasing the sample variance c. Increasing the sample size d. Increasing the size of the sample mean difference

c. Increasing the sample size

Which of the following studies uses a matched-subjects design? a. None of the other options is a matched-subjects design. b. A sample of children is tested for vocabulary skills at age six and then again at age ten. c. Participants are assigned to one of two treatment groups so that each participant in one group has the same IQ as a participant in the other group. d. A group of twins is tested for visual acuity on one day and then tested again the following day after receiving a drug.

c. Participants are assigned to one of two treatment groups so that each participant in one group has the same IQ as a participant in the other group.

The null hypothesis for a repeated-measures test states: a. None of these. b. The overall sample will have a mean difference of MD = 0. c. The entire population will have a mean difference ofμD = 0. d. Each individual will have a difference score of D = 0.

c. The entire population will have a mean difference ofμD = 0.

A repeated-measures design uses one group of participants with each individual measured in two conditions or at two different times. The difference between the two scores is found for each individual and the sample of difference score is used to test a hypothesis about the population of difference scores. What is the null hypothesis for the test? a. The sample mean difference is zero. b. The population mean difference is not equal to zero. c. The population mean difference is zero. d. The sample mean difference is not equal to zero.

c. The population mean difference is zero.

A repeated-measures study finds a mean difference of MD = 5 points between two treatment conditions. Which of the following sample characteristics is most likely to produce a significant t statistic for the hypothesis test? a. a large sample size (n) and a large variance b. a small sample size (n) and a small variance c. a large sample size (n) and a small variance d. a small sample size (n) and a large variance

c. a large sample size (n) and a small variance

The data from a repeated-measures research study show that all of the subjects scored about 10 points higher in treatment I than in treatment II. The sample of difference scores will produce a. a small sample variance and a small t statistic. b. a large sample variance and a large t statistic. c. a small sample variance and a large t statistic. d. a large sample variance and a small t statistic.

c. a small sample variance and a large t statistic.

A repeated-measures study produces a sample mean difference of MD = 4.5 with SS = 2400 for a sample of n = 25 individuals. Based on this information, what is the value of Cohen's d? a. d = 4.5/100 = 0.045 b. d = 4.5/2 = 2.25 c. d = 4.5/10 = 0.45 d. d = 4.5

c. d = 4.5/10 = 0.45

A researcher obtains t = 2.10 for a repeated-measures study using a sample of n = 16 participants. Based on this t value, what is the correct decision for a two-tailed test? a. cannot make a decision without additional information b. reject the null hypothesis with either α = .05 or α = .01 c. fail to reject the null hypothesis with either α = .05 or α = .01 d. reject the null hypothesis with α = .05 but not with α = .01

c. fail to reject the null hypothesis with either α = .05 or α = .01

A repeated-measures experiment and an independent-measures experiment both produce t statistics with df = 20. Which experiment used more subjects? a. They both used n = 22 subjects. b. They both used n = 21 subjects. c. independent measures d. repeated measures

c. independent measures

The repeated-measures t statistic uses one sample of difference scores to test a hypothesis about one population of difference scores. The t statistic has exactly the same structure as the single-sample t statistic presented in Chapter 9. A repeated-measures experiment and an independent-measures experiment both produce t statistics with df = 14. Which experiment used more subjects? a. They both used n = 16 subjects. b. They both used n = 15 subjects. c. independent measures d. repeated measures

c. independent measures

A researcher obtains a t statistic of t = 2.00 from a repeated measures study using n = 17 participants. If the effect size is measured using r2, then what is the value of r2? a. r2 = 4.00 b. The value of r2 cannot be determined from the information provided. c. r2 = 4/20 = 0.20 d. r2 = 4/16 = 0.25

c. r2 = 4/20 = 0.20

With α = .05 and a sample of n = 12 subjects in a repeated measures experiment, the two-tailed critical region for the t statistic has boundaries of ________. a. t = ±1.796 b. t = ±1.812 c. t = ±2.201 d. t = ±2.228

c. t = ±2.201

The repeated-measures t statistic uses the mean (MD) and the SS from one sample of difference scores to test a hypothesis about one population of difference scores. The t statistic has exactly the same structure as the single-sample t statistic presented in Chapter 9. If a researcher obtains a mean of MD = 4 with SS = 72 for a sample of n = 9 difference scores, then what is the estimated standard error for the sample mean difference? a. 3 b. 9 c. 8 d. 1

d. 1

What is the value for the estimated standard error for a set of n = 9 D scores with SS = 72? a. 3 b. 72 c. 9 d. 1

d. 1

A researcher obtains MD =2 with SS = 81 for a repeated-measures study using a sample of n = 10 participants. If the researcher measures effect size using Cohen's d, what value will be obtained for d? a. . 2 b. 2/9 c. 2/√3 d. 2/3

d. 2/3

For which of the following situations would a repeated-measures study be appropriate? a. Compare personality scores for individuals diagnosed with an eating disorder and those who are not diagnosed. b. Compare salary levels for college graduates and those who did not graduate from college. c. Compare attitude scores for males versus females. d. Compare reaction times before and after taking a pain medication.

d. Compare reaction times before and after taking a pain medication.

What is the effect of increasing sample variance for a repeated-measures study comparing two treatment conditions? a. It will increase the likelihood of rejecting the null hypothesis and decrease Cohen's d. b. It will decrease the likelihood of rejecting the null hypothesis and increase Cohen's d. c. It will increase the likelihood of rejecting the null hypothesis and increase Cohen's d. d. It will decrease the likelihood of rejecting the null hypothesis and decrease Cohen's d

d. It will decrease the likelihood of rejecting the null hypothesis and decrease Cohen's d

Which of the following sets of data is most likely to produce a significant t statistic? a. MD = 10 and SS = 100 b. MD = 2 and SS = 10 c. MD = 2 and SS = 100 d. MD = 10 and SS = 10

d. MD = 10 and SS = 10

Which of the following tends to occur when sample size is increased? a. The variance of the difference scores decreases. b. The sample mean difference decreases. c. All of the other options occur when sample size is increased. d. The standard error of the mean difference decreases

d. The standard error of the mean difference decreases

A researcher conducts an experiment comparing two treatment conditions and obtains 20 scores in each treatment. Which design would require the smallest number of subjects? a. an independent-measures design b. either an independent-measures or a matched-subjects design c. a matched-subjects design d. a repeated-measures design

d. a repeated-measures design

The repeated-measures t statistic uses one sample of difference scores to test a hypothesis about one population of difference scores. The t statistic has exactly the same structure as the single-sample t statistic presented in Chapter 9. If a researcher uses a repeated-measures study to compare two treatment conditions with a set of 20 scores in each treatment, then what is the df value for the repeated-measures t statistic? a. df = 18 b. df = 38 c. df = 39 d. df = 19

d. df = 19

The following data were obtained from a repeated-measures research study. What is the value of df for the t statistic? a. df = 9 b. df = 8 c. df = 5 d. df = 4

d. df = 4

Assuming that other factors are held constant, which of the following would tend to decrease the value of the t statistic (make it closer to zero)? a. None of the other 3 options would cause a decrease in the value of t. b. increase the sample size c. increase the sample mean difference d. increase the sample variance

d. increase the sample variance

The repeated-measures t statistic uses one sample of difference scores to test a hypothesis about one population of difference scores. The t statistic has exactly the same structure as the single-sample t statistic presented in Chapter 9. A researcher reports a t statistic with df = 24 from a repeated-measures research study. How many subjects participated in the study? a. n = 13 b. n = 23 c. n = 11 d. n = 25

d. n = 25

A major concern with a repeated-measures study is the possibility of ________. a. obtaining a mean difference that is due to individual differences rather than treatment differences b. negative values for the difference scores c. All of these options are major concerns. d. order effects

d. order effects

within-subjects design

random assignment for order (treatment first vs. control first)

Independent measures research design

random assignment to treatment(s) and control

matched-subjects design

research method in which individuals in one sample are paired with individuals in another sample