The following is a data set from an independent-measures study comparing the effects of caffeine on driving accuracy. (Higher scores = more mistakes on a driving test = less accuracy).
Caffeine Group No Caffeine Group
5 5
6 5
8 9
5 9
3 8
2 1
5 1
6 9
0 5
9 5
9. Calculate the mean and variance for the caffeine group and the no caffeine group
10. Do these data suggest that there is a difference between these groups at the .05 significance level (two-tailed)? (Do an independent samples t-test)
11. Calculate r2to measure the effect size.