A political science professor wonders if there is a difference in knowledge increase between students who review material with an SI and students who review on their own (without the SI). He randomly assigns students to one of two groups for one month: Group 1 is instructed to attend SI regularly; Group 2 is instructed to review material on their own. After one month, both groups are given a test to measure knowledge of the material. The following scores are obtained (higher scores = more knowledge acquired by the students and lower scores = less knowledge acquired by the students).

With SI (x1): 59 48 45 39 52 56 50 41 46 45 48

Without SI (x2): 36 42 48 37 51 32 47 38 40 31 20

What is the sample mean (X1)?

a. 48.091 b. 1.65 c. 48

What is the sample variance S2 (X1)? a. 32.446 b. 50 c. 5.696

What is the sample mean (X2)? a. 38.364 b. 39 c. 37

What is the sample variance S2 (X2)? a. 71.140 b. 8.434 c. 72

Which is Step 1? a. H0: 1 = 2 and H1: 1 2 b. H0: 1 2 and H1: 1 < 2 c. H0: 1 2 and H1: 1 > 2

What step 2? a. 2-tail; Alpha=.05; df=20; tcrit=2.086 b. 2-tail; Alpha=.05; df=22; tcrit=2.074 c. 1-tail; Alpha=.05; df=20; tcrit=1.725

What is step 3? a. Estimate of standard error of the difference between the means = 3.219 and tobt = 3.022 b. Estimate of standard error of the difference between the means = 3.022 and tobt = 3.219 c. Estimate of standard error of the difference between the means = 2.32 and tobt = 5.22

What is step 4? a. Reject H0 b. Retain H0

What is step 5? a. It appears that there is a significant difference in knowledge between students who reviewed with SI and students who reviewed on their own. b. It appears that there is no significant difference in knowledge between students who reviewed with SI and students who reviewed on their own.

What is the confidence interval? a. the confidence interval: 95% CI = (3.012, 16.442) b. we don't need to compute confidence interval

What is the effect size with interpretation? a. effect size = .313, which is a large effect size b. effect size = .151, small effect size