Professor Gosling wants to examine the effect of caffeine on depression. His research hypothesis is that a moderate dose (25 mg) of caffeine will lower depression scores on a psychological test when compared with no caffeine (placebo).
The null hypothesis is that:
a. depression scores with a moderate dose (25 mg) of caffeine = depression scores with no caffeine
b.depression scores with a moderate dose (25 mg) of caffeine > depression scores with no caffeine
c. depression scores with a moderate dose (25 mg) of caffeine >= depression scores with no caffeine