Us versus Them in Context: Meta-Analysis as a Tool for Geotemporal Trends in Intergroup Relations.

The increasing availability of studies from many nations offers important potential insights into group-based psychology and behavior, conflict, and violence. Nonetheless, to date, few cross-national or cultural comparisons of study findings have been made, representing a gap in our understanding of the historical causes and courses of intergroup conflict in current comparative approaches. Meta-analytic methods offer researchers the ability to combine data from studies with groups as well as across time. Our review of statistical methods available for comparative analyses in intergroup research found strengths and limitations for understanding group differences, conflict, and violence, and meta-analytic methods address these limitations by exploring potential structural-level moderators and by identifying how temporal and geographical variations may relate directly to group-based variables. Such methods can contribute to our understanding of broad structural effects on group-based variables by elucidating the mechanisms underlying them.