A biopsychologist studies role of brain chemical serotonin in aggression. One sample of rats serves as the control group and receives a placebo. A second sample of rats receives drug that lowers brain levels of serotonin. Then the researcher tests animals by recording the number of aggressive responses each of rats display. The data are given below.
| Low Serotonin |
Control |
| n = 4 |
n = 8 |
| M = 22 |
M = 14 |
| SS = 76 |
SS = 164 |
(a) Does the drug have a vital effect on aggression? Employ alpha level of .05, two tails.
a) Yes
b) No