Effect-size indices for dichotomized outcomes in meta-analysis

Psychol Methods. 2003 Dec;8(4):448-67. doi: 10.1037/1082-989X.8.4.448.


It is very common to find meta-analyses in which some of the studies compare 2 groups on continuous dependent variables and others compare groups on dichotomized variables. Integrating all of them in a meta-analysis requires an effect-size index in the same metric that can be applied to both types of outcomes. In this article, the performance in terms of bias and sampling variance of 7 different effect-size indices for estimating the population standardized mean difference from a 2 x 2 table is examined by Monte Carlo simulation, assuming normal and nonnormal distributions. The results show good performance for 2 indices, one based on the probit transformation and the other based on the logistic distribution.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Analysis of Variance*
  • Humans
  • Logistic Models
  • Meta-Analysis as Topic*
  • Monte Carlo Method
  • Psychology, Experimental / statistics & numerical data*
  • Psychometrics / statistics & numerical data*