HW 10 Problems 1 and 2 1. A researcher conducts an independent-measure 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 receive a drug that lowers levels of serotonin. Then the researcher tests the animals by recording the number of aggressive responses each of the rats display. The data are as follows. Control n =10 M = 14 SS = 180.5 Low Serotonin n = 15 M = 19 SS = 130.0 a. Does the drug have a significant effect on aggression? Use an alpha level of .05, two-tails. b. Compute Cohen's d to measure the size of the treatment effect. 2 . The following data are from an independent-measures experiment comparing two treatment conditions. Treatment 1 Treatment 2 4 19 5 11 12 18 10 10 10 12 7 14 a. Do these data indicate a significant difference between the treatments at the .05 level of significance? b. Compare r2 to measure the size of the treatment effect. c. Write a sentence demonstrating how the outcome of the hypothesis test and the measure of effect size would appear in a research report