An Evaluation of Rosenthal and Rubin’s Binomial Effect Size Display

The binomial effect size display (BESD) has been proposed by Rosenthal and Rubin (1979 , 1982 ; Rosenthal, 1990 ; Rosenthal & Rosnow, 1991) as a format for presenting effect sizes associated with certain experimental and nonexperimental research. An evaluation of the BESD suggests that its application is limited to presenting the results of 2 × 2 tables where φ is employed as the index of effect size. Findings indicate that the BESD provides little added information beyond an examination of the raw percentages in the 2 × 2 table and dramatically distorts effect sizes when binomial success rates vary from .50.