This paper demonstrates the variety of positive-skew phenomena and discusses their theoretical, research, and practical implications in education. (PN)

Comments on some methodological limitations of the research base of "The Bell Curve": blind use of the normal distribution (bell curve); avoidance of nonnormal statistical distributions, which are more appropriate for some social and economic characteristics; copious use of percentiles and quintiles, inappropriate with nonnormal…

The second approach used by L. V. Hedges and L. Friedman (1993) in their reanalysis of Feingold's earlier results is conceptually equivalent and yields results consistent with the original interpretation. The first method yields results that are discrepant. Analyses of variations in tail effect sizes are planned. (SLD)

Feingold's reply illustrates that his steps in characterizing tail effect sizes are not the calculations the authors had imagined. Attempting to reproduce Feingold's calculations, the authors still often find themselves in disagreement with interpretations Feingold has placed in his table. (SLD)

The purpose of this paper is to discuss ways in which developmental psychology suffers from the lack of an appropriate technology of measurement and statistical analysis. The paper begins by noting that developmental psychology is the study of change; that individuals develop through a succession of "stages" which are separated by…

Analyzes effect sizes in tails of distribution of scores in Feingold's study of joint effects of gender differences in mean and variability on 28 cognitive-ability scales. Effect sizes are smaller than Feingold assumed. Evaluates joint effect of gender differences by number of males and females in extreme score ranges. (SLD)