Effect Size - Texas Tech University
www.depts.ttu.edu › aged › toolboxB. Cohen’s “effect size” index: d (Cohen, 1988, pp. 19-74) 1. d = a standardized effect size index. 2. The raw difference (in the original measurement unit) between the sample means on the de pendent va riable is divided by the estimated pooled standa rd deviation of the dependent variable in the populations from which random