Download Chapter 11 Practice Exam

Chapter 11 Practice Exam
Multiple Choice
Identify the choice that best completes the statement or answers the question.
____
1. If a researcher is using a t statistic to test a null hypothesis about a population, what information is
needed from the population to calculate the t statistic?
a. You must know the population mean.
b. You must know the population variance or standard deviation.
c. You must know the population mean and the variance or standard deviation.
d. The t statistic does not require any information about the population.
____
2. A sample of n = 4 scores has SS = 60. What is the variance for this sample?
a. 30
c. 16
b. 20
d. 15
____
3. A sample with a mean of M = 40 and a variance of s2 = 20 has an estimated standard error of 1 point.
How many scores are in the sample?
a. 4
b. 5
c. 20
d. 21
____
4. Which of the following samples will have the smallest value for the estimated standard error?
a. n = 4 with s2 = 16
c. n = 16 with s2 = 16
b. n = 4 with s2 = 64
d. n = 16 with s2 = 64
____
5. A researcher conducts a hypothesis test using a sample of n = 20 from an unknown population. What
is the df value for the t statistic?
a. 19
b. 20
c. 21
d. Cannot be determined from the information given
____
6. A researcher is using a two-tailed hypothesis test with  = .05 to evaluate the effect of a treatment. If
the boundaries for the critical region are t = ± 2.080, then how many individuals are in the sample?
a. n = 22
b. n = 21
c. n = 20
d. Impossible to determine without more information
____
7. If other factors are held constant, which set of sample characteristics is most likely to produce a
significant t statistic?
a. n = 25 with s2 = 100
b. n = 25 with s2 = 400
____
c. n = 100 with s2 = 100
d. n = 100 with s2 = 400
8. A sample of n = 16 scores produces a t statistic of t = 2.00. If the sample is used to measure effect
size with r2, what value will be obtained for r2?
a. r2 = 2/20
c. r2 = 2/19
2
b. r = 4/20
d. r2 = 4/19
____
9. A sample is selected from a population with  = 46, and a treatment is administered to the sample.
After treatment, the sample mean is M = 48 with a sample variance of s2 = 16. Based on this
information, what is the value of Cohen’s d?
a. d = 0.125
b. d = 0.25
c. d = 0.50
d. Cohen’s d cannot be computed without knowing the sample size.
____ 10. A sample is selected from a population with  = 70, and a treatment is administered to the sample.
After treatment, the sample mean is M = 74, and Cohen’s d is d = 1.00. What is the value of the
sample variance?
a. s2 = 2
b. s2 = 4
c. s2 = 16
d. It is impossible to determine the sample variance without more information.
____ 11. If a sample of n = 16 scores is being used to make an 80% confidence interval estimate of the
population mean, , what value(s) of t should be used?
a. t = 0
c. t = ±1.753
b. t = ±2.131
d. t = ±1.341
____ 12. Which of the following research situations would be most likely to use an independent-measures
design?
a. Examine the development of vocabulary as a group of children mature from age 2
to age 3
b. Examine the long-term effectiveness of a stop-smoking treatment by interviewing
subjects 2 months and 6 months after the treatment ends
c. Compare the mathematics skills for 9th-grade boys versus 9th-grade girls
d. Compare the blood-pressure readings before medication and after medication for a
group a patients with high blood pressure
____ 13. Which of the following is the correct null hypothesis for an independent-measures t test?
a. 1 – 2 = 0
c. 1 – 2 0
b. M1 – M2 = 0
d. M1 – M2 0
____ 14. An independent-measures study has one sample with n = 6 and a second sample with n = 8 to
compare two experimental treatments. What is the df value for the t statistic for this study?
a. 7
c. 13
b. 12
d. 14
____ 15. One sample of n = 8 scores has a variance of s2 = 6 and a second sample of n = 8 scores has s2 = 10.
If the pooled variance is computed for these two samples, then the value obtained will be ______.
a. closer to 6 than to 10
b. closer to 10 than to 6
c. exactly halfway between 6 and 10
d. cannot be determined without more information
____ 16. Two samples, each with n = 5 scores, have a pooled variance of 40. What is the estimated standard
error for the sample mean difference?
a. 4
b. 8
c. 10
d. 20
____ 17. The data from an independent-measures research study produce a sample mean difference of 4
points and a pooled variance of 18. If there are n = 4 scores in each sample, what is the estimated
standard error for the sample mean difference?
a. 3
c. 12
b. 9
d. The square root of 12
____ 18. An independent-measures research study uses two samples, each with n = 15 participants. If the data
produce a t statistic of t = 2.760, which of the following is the correct decision for a two-tailed
hypothesis test?
a. Reject the null hypothesis with  = .05 but fail to reject with  = .01
b. Reject the null hypothesis with either  = .05 or  = .01
c. Fail to reject the null hypothesis with either  = .05 or  = .01
d. Cannot answer without additional information
____ 19. The results of an independent-measures research study are reported as “t(22) = 2.12, p < .05, two
tails.” For this study, what t values formed the boundaries for the critical region?
a. ±2.080
c. ±2.069
b. ±2.074
d. ±2.064
____ 20. An independent-measures study produces sample means of M1 = 20 and M2 = 17. If both samples
have n = 18 scores and Cohen’s d = 0.50, what is the value for the pooled variance?
a. 2
c. 6
b. 4
d. 36
____ 21. A researcher predicts that scores in treatment A will be higher than scores in treatment B. Which of
the following is the correct null hypothesis for a one-tailed test evaluating this prediction?
a. A > B
c. A > B
b. A < B
d. A < B
____ 22. For the independent-measures t statistic, what is the effect of increasing the sample variances?
a. Increase the likelihood of rejecting H0 and increase measures of effect size
b. Increase the likelihood of rejecting H0 and decrease measures of effect size
c. Decrease the likelihood of rejecting H0 and increase measures of effect size
d. Decrease the likelihood of rejecting H0 and decrease measures of effect size
____ 23. Which of the following sets of data would produce the largest value for Cohen’s d?
a. n = 10 for both samples, a pooled variance of 15, and a mean difference of 3 points
b. n = 20 for both samples, a pooled variance of 15, and a mean difference of 5 points
c. n = 10 for both samples, a pooled variance of 20, and a mean difference of 3 points
d. n = 20 for both samples, a pooled variance of 20, and a mead difference of 5 points
____ 24. Which set of sample characteristics is most likely to produce a significant value for the
independent-measures t statistic and a large measure of effect size?
a. A small mean difference and small sample variances
b. A large mean difference and small sample variances
c. A small mean difference and large sample variances
d. A large mean difference and large sample variances
____ 25. For which of the following situations would a repeated-measures research design be appropriate?
a. Comparing mathematical skills for girls versus boys at age 10
b. Comparing pain tolerance with and without acupuncture needles
c. Comparing self-esteem for students who participate in school athletics versus those
who do not
d. Comparing verbal solving skills for science majors versus art majors at a college
____ 26. The following data were obtained from a repeated-measures research study. What is the value of MD
for these data?
Subject 1st
#1
10
#2
4
#3
7
#4
6
a.
b.
c.
d.
2nd
15
8
5
11
3
3.5
4
4.5
____ 27. A repeated-measures study using a sample of n = 20 participants would produce a t statistic with df
= ____.
a. 9
b. 19
c. 20
d. 39
____ 28. A repeated-measures study and an independent-measures study both produced a t statistic with df =
10. How many individuals participated in each study?
a. 12 for repeated-measures and 11 for independent-measures
b. 12 for repeated-measures and 12 for independent-measures
c. 11 for repeated-measures and 11 for independent-measures
d. 11 for repeated-measures and 12 for independent-measures
____ 29. Which of the following is the correct null hypothesis for a repeated-measures t test?
a. MD = 0
c. 1 = 2
b. D = 0
d. M1 = M2
____ 30. A repeated-measures study comparing two treatments with n = 4 participants produces MD = 2 and
SS = 75 for the difference scores. What is the estimated standard error for the sample mean
difference?
a. 25
c. 5
b. 25/4 = 6.25
d. 2.5
____ 31. A sample of difference scores has a mean of MD = 5 with a variance of s2 = 100. If effect size is
measured using Cohen’s d, what is the value of d?
a. d = 5/10
b. d = 5/100
c. d = 25/100
d. Cannot determine without knowing the sample size
____ 32. A research report describing the results from a repeated-measures study states that the data show no
significant difference between the two treatments, t(10) = 1.65, p > .05. Based on this report, how
many individuals participated in the research study?
a. 9
c. 11
b. 10
d. 12
____ 33. In general, if the variance of the difference scores increases, what will happen to the value of the t
statistic?
a. It will increase (move farther toward the tail of the distribution).
b. It will decrease (move toward 0 at the center of the distribution).
c. It will stay the same; the t statistic is not affected by the variance of the difference
scores.
d. It may increase or may decrease; there is no consistent relationship between
variance and the size of the t statistic.
____ 34. If other factors are held constant, which of the following sets of data is most likely to produce a
significant value for the repeated-measures t statistic?
a. n = 15 and MD = 2
c. n = 30 and MD = 2
b. n = 15 and MD = 4
d. n = 30 and MD = 4
____ 35. Which of the following will not increase the width of a confidence interval?
a. Increase the percentage of confidence from 80% to 90%
b. Reduce the sample size from n = 25 to n = 16
c. Increase the sample mean from MD = 2 to MD = 4
d. All of the other options will increase the width of a confidence interval.
Chapter 11 Practice Exam
Answer Section
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