A researcher conducts an independent - measures study examining the effectiveness of a group exercise program at an assisted living facility for elderly adults. One group of residents is selected to participate in the program, and a second group serves as a control. After 6 weeks, the researcher records a combined score measuring balance and strength for each individual. The data are as follows :

Control Exercise

n = 10 n = 15

M =12 M =15.5

SS = 120.5 SS = 190.0

a. Does the exercise program have a significant effect ? Use an alpha level of .05, two tails.

b. Compute Cohen's d to measure the size of the treatment effect.