Question

The results of a single-sample t test are reported as t(44) = −3.35, p < .001, d = −0.50. Describe the effect size for this study.

Answer 1

Solution:

Given:  

t₍₄₄₎ = −3.35,

p < .001,

d = −0.50

From p-value, we can conclude that: there is significant difference in mean. Thus we need to know how much effect of this difference. Thus we calculate Cohen's d for effect size.

It is d = -0.50 , we use absolute value

thus d = 0.50

Following are different interpretations for Cohen's d.

d = 0.2 is considered as small effect

d = 0.5 is considered as medium effect

d = 0.8 is considered as large effect.

Since d = 0.50 , there is medium effect.