Unlocking the Benefits of Gender Diversity: How an Ecological-Belonging Intervention Enhances Performance in Science Classrooms.

Gender diversity signals inclusivity, but meta-analyses suggest that it does not boost individual or group performance. This research examined whether a social-psychological intervention can unlock the benefits of gender diversity on college physics students' social and academic outcomes. Analyses of 124 introductory physics classrooms at a large research institution in the eastern United States (N = 3,605) indicated that in classrooms doing "business as usual," cross-gender collaboration was infrequent, there was a substantial gender gap in physics classroom belonging, and classroom gender diversity had no effect on performance. The ecological-belonging intervention aimed to establish classroom norms that adversity in the course is normal and surmountable. In classrooms receiving the intervention, cross-gender interaction increased 51%, the gender gap in belonging was reduced by 47%, and higher classroom diversity was associated with higher course grades and 1-year grade point average for both men and women. Addressing contextual belongingness norms may help to unlock the benefits of diversity.

Power to Detect What? Considerations for Planning and Evaluating Sample Size.

ACADEMIC ABSTRACT: In the wake of the replication crisis, social and personality psychologists have increased attention to power analysis and the adequacy of sample sizes. In this article, we analyze current controversies in this area, including choosing effect sizes, why and whether power analyses should be conducted on already-collected data, how to mitigate the negative effects of sample size criteria on specific kinds of research, and which power criterion to use. For novel research questions, we advocate that researchers base sample sizes on effects that are likely to be cost-effective for other people to implement (in applied settings) or to study (in basic research settings), given the limitations of interest-based minimums or field-wide effect sizes. We discuss two alternatives to power analysis, precision analysis and sequential analysis, and end with recommendations for improving the practices of researchers, reviewers, and journal editors in social-personality psychology. PUBLIC ABSTRACT: Recently, social-personality psychology has been criticized for basing some of its conclusions on studies with low numbers of participants. As a result, power analysis, a mathematical way to ensure that a study has enough participants to reliably "detect" a given size of psychological effect, has become popular. This article describes power analysis and discusses some controversies about it, including how researchers should derive assumptions about effect size, and how the requirements of power analysis can be applied without harming research on hard-to-reach and marginalized communities. For novel research questions, we advocate that researchers base sample sizes on effects that are likely to be cost-effective for other people to implement (in applied settings) or to study (in basic research settings). We discuss two alternatives to power analysis, precision analysis and sequential analysis, and end with recommendations for improving the practices of researchers, reviewers, and journal editors in social-personality psychology.