Question

Kaplan is interested in determining if the average mathematics GRE score improved for students who took their preparation course. The GRE Math section is scored on a130-170 point scale, in 1 point increments. To conduct this study, 10 students who tookthe GRE and then retook it after taking their course were randomly picked from thepopulation. Their scores before and after are noted below:

Before

A. 147

B. 152

C. 155

D. 138

E. 147

F. 153

G. 151

H. 158

I. 140

J. 153

After

A. 152

B. 148

C. 160

D. 163

E. 150

F. 148

G. 152

H. 158

I. 146

J. 151

i. If we were to conduct a significance test for this experiment, what would the alter-native hypothesis be?

ii. Have all assumptions to construct a 95% CI been met for this experiment? If no, which assumption was violated? If yes, then compute the 95% confidence intervaland give the interpretation of this CI.

Answer 1

i. If we were to conduct a significance test for this experiment, what would the alter-native hypothesis be?

Ho:

_d = 2 - 1 where 2 - after and 1 - before

ii. Have all assumptions to construct a 95% CI been met for this experiment? If no, which assumption was violated? If yes, then compute the 95% confidence intervaland give the interpretation of this CI.

Paired T for AFTER - before

             N    Mean StDev SE Mean
AFTER       10 152.80   5.65     1.79
before      10 149.40   6.42     2.03
Difference 10    3.40   8.50     2.69

95% CI for mean difference: (-2.68, 9.48)
T-Test of mean difference = 0 (vs ≠ 0): T-Value = 1.26 P-Value = 0.238