Step 4

If appropriate, calculate Cohen's d for this study. What size effect did you have?

A sample of n = 585 college students were selected to participate in the study. The mean score on the stress scale for the sample was M = 28.57 with SD = 2.518.

Research Question:

Did the participants in the study score significantly higher on the Stress Subscale pre-treatment than the normal population whose mean is = 18.08?

H₀: 18.08

H_A: > 18.08

Using standard normal distribution, we find the critical value at 584 degrees of freedom and significance

level of .05= 1.6475.

We reject the null hypothesis and conclude there is enough evidence to claim that the participants in the study score significantly higher on the Stress Subscale pre-treatment than the normal population.

lable 4 Pretreatment, Post-treatment, and Follow-up Symptoms by Condition Measure Treatment Control Pretreatment Post-treatment Follow-up Pretreatment Post-treatment Follow-up M (SD) M (SD) M (SD) M (SD) M (SD) M (SD) Stress 28.77 (6.12) 22.98 (9.64) 21.77 (9.87) 28.04 (6.15) 23.84 (9.18) 23.57 (9.20) Anxiety 21.11 (9.26) 15.82 (10.81) 15.98 (10.46) 19.84 (9.34) 15.60 (10.17) 15.63 (10.14) Depression 25.83 (10.34) 19.90 (12.32) 19.86 (12.08) 24.31 (10.65) 20.80 (11.98) 20.71 (11.79) Note. N = 585. Stress, Anxiety, and Depression scores had a possible range of 0-42