A researcher conducts a study examining how the brain chemical serotonin is related to aggression. One sample of rats serves as a control group and receives a placebo that does not affect normal...

A researcher conducts a study examining how the brain chemical serotonin is related to aggression. One sample of rats serves as a control group and receives a placebo that does not affect normal levels of serotonin. A second sample of rats receives a drug that lowers brain levels of serotonin. Then the researcher records the number of aggressive responses each of the rats displays in a test. The sample statistics are as follows.

Control:  =n1=10    -x1=14 ss1 =180.5

Low Serotonin:   n2=15    -x2=19 ss2=130.0

1. Does the drug have a significant effect on aggression? Use level of .05.

1. Compute the 95% confidence interval estimate on the difference in the mean aggression between the control and the experiment condition. Interpret the result.

1. Compute the effect size and interpret the result.