A researcher would like to determine if relaxation training will affect the number of headaches for chronic headache sufferers. For a week prior to training, each participant records the number of headaches suffered. Participants then receive relaxation training, and for the week following training the number of headaches is again measured. The number of headaches before and after training are provided in the table.

a. Compute the table to compute SS for the sample of difference scores.

b. Do the results indicate a significant difference? Use a two-tailed test with = .05.

c. Compute Cohen's d and r 2 and state the size of each effect.

Participant (Before) X1 (After) X2 Difference Score: D D-MD (D-MD) 2

Participants	Before X1	After X2	Difference Score:D	D-MD	(D-Md)2
A	7	2	-5	-2
B	3	2	-1	2
C	7	3	-4	-1
D	4	1	-3	0
E	11	5	-6	-3
F	13	5	-8	-5
G	6	6	0	3
H	7	8	1	4
I	11	10	-1	2
			md=-3		ss=