Question

A sports psychologist wants to know if weight training leads to more positive mood. To assess the effects of weight training on mood, she obtained a sample of 10 people who had never weight trained and measured their mood. She then instructed them in proper weight training techniques and had them follow a training program for one month. At the end of the month the participants’ mood was measured again. The mood scale was scored such that higher numbers indicate more positive mood. D is computed after—prior.

1. Compute the effect size for this study: a) 0.66, b) 2.08, c) 0.43, d) 1.83

2. How large is this effect: a) small, b) small-medium, c) medium, d) large

3. Which of the following is the best summary of the results of this study: a) Participants reported a significantly more positive mood after weight training than before weight training, b) Participants reported a significantly less positive mood after weight training than before weight training, c) there was no significant difference between the moods prior to weight training and the moods after weight training.

Participant	Prior to Weight Training	After Weight Training	D (after—prior)
1	5	7
2	4	6
3	3	6
4	2	1
5	5	6
6	6	7
7	7	7
8	6	5
9	2	4
10	6	6

Answer 1

Effect size= MEAN/S.D=0.9/1.37= 0.66 OPTION A

EFFECT IS MEDIUM

Participants reported a significantly more positive mood after weight training than before weight training,