title: Heterogeneity Coefficients for Mahalanobis' D as a Multivariate Effect Size.
abstract: The Mahalanobis distance D is the multivariate generalization of Cohen's d and can be used as a standardized effect size for multivariate differences between groups. An important issue in the interpretation of D is heterogeneity, that is, the extent to which contributions to the overall effect size are concentrated in a small subset of variables rather than evenly distributed across the whole set. Here I present two heterogeneity coefficients for D based on the Gini coefficient, a well-known index of inequality among values of a distribution. I discuss the properties and limitations of the two coefficients and illustrate their use by reanalyzing some published findings from studies of gender differences.
authors.affiliation: a Department of Psychology , University of New Mexico.
authors.forename: Marco
authors.initials: M
authors.lastname: Del Giudice
mesh_terms: D000374:Aggression; D000465:Algorithms; D001921:Brain / Q000000981:diagnostic imaging / Q000502:physiology; D003627:Data Interpretation, Statistical; D005260:Female; D005783:Gender Identity; D006126:Group Processes; D006801:Humans; D008297:Male; D015201:Meta-Analysis as Topic; D015999:Multivariate Analysis; D009790:Occupations; D010551:Personality; D012727:Sex Characteristics; D012984:Software; D013850:Thinking
keywords: Effect size; Mahalanobis distance; group differences; heterogeneity; multivariate