T-test for difference in means: + $2 and df for the t-distribution = N1+ Nz -2 tobtained = X1 42 where Sx-x = SX - X n1 n2 Difference in proportions: P1 -P2 where Spup = P. (1 - P.) NitN2 and P* = Zobtained = NIN2 N1+N2 SP-PAlpha N1 N2 Df (use N1+N2-2) t-critical (+/-) 05 15 10 05 9 12 .05 29 33 01 29 33 05 Infinity | infinity2. You are interested in gender differences in alcohol use among college students, and your literature review suggests that male college students drink more often than female students, on average. At your own university, you collect data that shows the following among a sample of undergraduates who report drinking at all: Mean drinking Gender N occasions per month St. Deviation Males 15 6.47 0.40 Females 17 4.37 0.30 Perform a t-test to assess whether men drink at a different rate, on average, than women at your university. In performing this test, answer the following questions: a. State your research and null hypotheses. b. What is the value of t that you obtain from these data (hand-calculate this)? c. What are your degrees of freedom? d. Using an alpha-level of .05, what is your critical value of t? e. What do you conclude? Do men drink more than women? That is, is the difference reported here statistically significant