Notes that because estimates of effect sizes are often either misreported or not reported at all, meta-analysts must use conversion formulas that allow estimates of effect sizes from information available. Focuses on formulas that convert "F" in ANOVA, a statistical test, to eta-squared, "d," or the correlation equivalent. Demonstrates that the…

A distribution theory is derived for a G. V. Glass-type (1976) estimator of effect size from studies involving paired comparisons. The possibility of combining effect sizes from studies involving a mixture of related and unrelated samples is also explored. Resulting estimates are illustrated using data from previous psychiatric research. (SLD)

This Monte Carlo study explored relationships among standard and unstandardized regression coefficients, structural coefficients, multiple R_ squared, and significance level of predictors for a variety of linear regression scenarios. Ten regression models with three predictors were included, and four conditions were varied that were expected to…

In contrast to the average effect sizes of the approach to metanalysis that can be thought of as literature synthesis, an effect-size surface is proposed as a function of scientifically relevant factors, estimated by extrapolating a response surface of observed effect sizes to a region of ideal studies. (SLD)

Kendall's Tau is often considered equivalent to Spearman's Rho as an ordinal measure of correlation in spite of its different metric. Formulas for converting Tau to Rho are reviewed; and a table of corresponding values is presented for Tau, Rho, and several related indices. (SLD)

Parametric measures to estimate J. Cohen's effect size (1966) from a single experiment or for a single study in meta-analysis are investigated. The main objective was to examine the principal statistical properties of this effect size--delta--under variance homogeneity, variance heterogeneity with known variance ratios, and for the Behrens-Fisher…

A meta-analysis of studies conducted between 1974 and mid-1987 on sex differences in mathematical tasks is presented. Methods used include estimations of: (1) parameters for a random effects model, and (2) coefficients for a linear-regression equation, all based on effect sizes calculated from each study. Differences have been decreasing. (TJH)

Results obtained in a metanalysis using indirect alternative methods of computing standardized mean difference effect sizes (SMDESs) were compared with results obtained from direct calculations of SMDESs. In most cases, alternative methods yield very comparable results and are beneficial to use, especially when sample sizes are large. (SLD)

The use of statistical methods to combine the results of independent empirical research studies (metanalysis) has a long history, with work mainly divided into tests of the statistical significance of combined results and methods for combining estimates across studies. Methods of metanalysis and their applications are reviewed. (SLD)

Barcikowski has provided tables for use in situations where means are to be used as the unit of analysis. This article argues that the conditions specified for use of these tables are not practical. It explicates a methodology for carrying out analyses based on group means. (Author/JAZ)

Methodology is suggested for several statistical procedures to detect polytomously scored items that function differently for two subgroups of examinees. The 3 methods are alternative ways of combining the data from 2 x "k" tables. Simulation results demonstrate the superiority of two of the methods, designated HW1 and HW3. (SLD)

Statistical methodologists have sometimes criticized the use of conventional statistics in meta-analysis, and in recent years a number of them have advocated the use of a special new statistical methodology for research synthesis. An examination of recent books describing this methodology shows that it is seriously limited in its applicability to…

The degree to which reliability affects the power of analysis of variance (ANOVA) tests involving one factor with two and three samples was quantified and tabulated by taking into account sample size, level of significance, and true score effect size. Results confirm a substantial effect on power. (SLD)

Three strategies for augmenting the interpretation of significance test results are illustrated. Determining the most suitable indices to use in evaluating empirical results is a matter of considerable debate among researchers. Researchers increasingly recognize that significance tests are very limited in their potential to inform the…

An evaluation of the rules-of-thumb used to determine the minimum number of subjects required to conduct multiple regression analyses suggests that researchers who use a rule of thumb rather than power analyses trade simplicity of use for accuracy and specificity of response. Insufficient power is likely to result. (SLD)