7.13 Treatment:x 1 ¼ 701 :9,s 1 ¼ 32 :8; control:x 2 ¼ 656 :1,s 2 ¼ 22 :5.
sp¼ 29 : 6
t¼ 3 : 45 ;17 df; p< 0 : 01
7.14 sp¼ 9 : 3
t¼ 4 : 71 ; pF 0
7.15 Weight gain:sp¼ 14 : 4
t¼ 2 : 30 ; p< 0 : 05
Birth weight:sp¼ 471 : 1
t¼ 2 : 08 ; p< 0 : 05
Gestational age:sp¼ 15 : 3
tF 0 ; pF 0 : 5
7.16 Sum of ranks: bulimic adolescents, 337.5; healthy adolescents, 403.5.
mH¼
ð 15 Þð 15 þ 23 þ 1 Þ
2
¼ 292 : 5
sH¼
ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
ð 15 Þð 23 Þð 15 þ 23 þ 1 Þ
12
r
¼ 33 : 5
z¼
403 : 5 292 : 5
33 : 5
¼ 3 : 31 ; pF 0
7.17 Sum of ranks: experimental group, 151; control group, 39.
mE¼
ð 12 Þð 12 þ 7 þ 1 Þ
2
¼ 120
sE¼
ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
ð 12 Þð 7 Þð 12 þ 7 þ 1 Þ
12
r
¼ 11 : 8
z¼
151 120
11 : 8
¼ 262 ; p¼ 0 : 0088
522 ANSWERS TO SELECTED EXERCISES