13. An independent-measures study uses n = 15 participants in each group to compare two treatment conditions. What is the df value for the t-statistic for this study?

a.14

b.15

c.28

d.29

14. An independent-measures research study uses two samples, each with n = 10 participants. If the data produce a t-statistic of t = 2.095, 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

15. 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