An independent-measures research study with n = 5 participants in each treatment produces sample variances of 8 and 10,and a 2-point difference between the two treatment means.Given this information,what is the value of Cohen's d?

Question

Quizplus · Accepted Answer

Cohen's d can be calculated using the formula: d = (M1 - M2) / SDpooled, where SDpooled is the pooled standard deviation. Since the sample variances are different (8 and 10), we need to use the formula for calculating SDpooled for independent-measures t-tests: SDpooled = sqrt[((n1-1)*S1^2 + (n2-1)*S2^2)/(n1+n2-2)]. Plugging in the values, we get SDpooled = sqrt[((4*8) + (4*10))/(5+5-2)] = sqrt[72] = 8.49. Therefore, d = 2/8.49 = 0.24, which is closest to choice B (2/3).

An Independent-Measures Research Study with N = 5 Participants in Each