17. Keeping everything else constant, if we changed from a one-tailed to a two-tailed test, we would expect power to:

a. Remain unchanged

b.Decrease

c. Increase

d. It is impossible to determine

18. Two samples from the same population both have M = 84 and s² = 20, but one sample has n = 10 and the other has n = 20 scores. Both samples are used to evaluate a hypothesis stating that = 80 and to compute Cohen's d. How will the outcomes for the two samples compare?

a. The larger sample is more likely to reject the null hypothesis and produce a larger value for Cohen's d.

b. The larger sample is more likely to reject the null hypothesis, but the two samples will have the same value for Cohen's d.

c. The larger sample is less likely to reject the null hypothesis and produce a larger value for Cohen's d.

d. The larger sample is less likely to reject the null hypothesis, but the two samples will have the same value for Cohen's d.

Section III: Single Sample t-test

19. A researcher conducts a hypothesis test using a sample of n = 20 from for a one-sample t. What is the df value for the t statistic?

a. 19

b. 20

c. 21

d. Cannot be determined from the information given

20. 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.

21. A sample of n = 9 scores has a variance of s² = 36. What is the estimated standard error for the sample mean?

a.1

b.2

c.4

d.16

22. Which of the following samples will have the smallest value for the estimated standard error?

a.n = 4 with s² = 16

b.n = 4 with s² = 64

c.n = 16 with s² = 16

d.n = 16 with s² = 64

23. With = .01, the two-tailed critical region for a t test using a sample of n = 16 subjects would have boundaries of ______. Consult the t-distribution table at the end for the information that you need.

a.t = 2.602

b.t = 2.583

c.t = 2.947

d.t = 2.921

24. 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