“…Our review of papers published since 1977 led to very similar conclusions. Based on data presented by Cascio et al (1991), Feild, Bayley, andBayley (1977), Hennessy and Merrifield (1978), Kesselman and Lopez (1979), Mercer (1984), Morstain (1984), Sandoval (1982), , we estimated the mean and standard deviation of the reported SD ratios to be .96 and .24, respectively (estimates of the distribution of group mean differences were obtained from this same set of studies). In our simulations, we used SD ratio values of .70, .95, and 1.20 to approximate the 15th, 50th, and 85th percentiles of the distribution of the ratio of lower-scoring to higherscoring group standard deviations.…”