(a)

(b)

B

SE B

β

B

SE B

β

Step 1

Step 1

Constant

76.91

2.98

Constant

76.20

2.71

Study Group

−13.46

2.62

−0.50^*

Study Group

−10.43

2.38

−0.44^*

Step 2

Constant

113.18

8.08

Study Group

−12.85

2.33

−0.48^*

Age

−0.67

0.14

−0.41^*