Effect sizes and effect size benchmarks in family violence research

Abstract

Scholarly journals increasingly request that authors include effect size (ES) estimates when reporting statistical results. However, there is little guidance on how authors should interpret ESs. Consequently, some authors do not provide ES interpretations, or, when interpretations are provided, they often fail to use appropriate reference groups, using instead the ES benchmarks suggested by Cohen (1988). After discussing the most commonly used ES estimates, we describe the method used by Cohen (1962) to develop ES benchmarks (i.e., small, medium, and large) for use in power analyses and describe the limitations associated with using these benchmarks. Next, we establish general benchmarks for family violence (FV) research. That is, we followed Cohen's approach to establishing his original ES benchmarks using family violence research published in 2021 in Child Abuse & Neglect, which produced a medium ES (d = 0.354) that was smaller than Cohen's recommended medium ES (d = 0.500). Then, we examined the ESs in different subspecialty areas of FV research to provide benchmarks for contextualized FV ESs and to provide information that can be used to conduct power analyses when planning future FV research. Finally, some of the challenges to developing ES benchmarks in any scholarly discipline are discussed. For professionals who are not well informed about ESs, the present review is designed to increase their understanding of ESs and what ES benchmarks tell them (and do not tell them) with respect to understanding the meaningfulness of FV research findings.

Keywords: Confidence intervals; Effect size benchmarks; Effect size interpretations; Effect sizes; Family violence research.