A researcher reports that the mean difference in response time to an auditory versus a visual cue is 0.83 s,with a pooled sample variance equal to 2.45.What is the effect size for this test using estimated Cohen's d?
A) d = 0.53; medium effect size
B) d = 0.53; large effect size
C) d = 0.34; small effect size
D) d = 0.34; medium effect size

Question

Quizplus · Accepted Answer

Cohen's d is calculated as the mean difference divided by the square root of the pooled variance. Here, d = 0.83 / sqrt(2.45) ≈ 0.53. According to Cohen's conventions, 0.2, 0.5, and 0.8 represent small, medium, and large effect sizes, respectively. Thus, 0.53 indicates a medium effect size.

A Researcher Reports That the Mean Difference in Response Time