The psychologists are interested in whether depressed people undergoing group therapy will perform a different number of activities of daily living before and after group therapy. Therefore, the psychologists have randomly selected 8 depressed clients in a 6-week group therapy program. Use the five steps of hypothesis testing to determine whether the observed differences in numbers of activities of daily living (shown below) obtained before and after therapy are statistically significant at the .05 level of significance (and, for practice, at the .01 level).

Question

Client--Before therapy--After therapy
A--12--17
B--7--15
C--10--12
D--13--21
E--9--16
F--8--18
G--14--17
H--11--8

#1-You calculated the standard deviation of the means. What was the standard deviation?

3.78
2.06
1.49
1.01

#2- You estimated the variance of the population of difference scores from the sample of difference scores. What the population variance?

20.32
17.71
15.75
18.98

Answer 1

Try a correlated groups (or dependent groups) t-test for this problem.