Group Size and Its Impact on Diversity in Hiring Decisions

Groups in organizations—such as boards of directors and work teams—often vary dramatically in size. We show that the size of a group plays a key role in decisions about whether to increase the diversity of its membership. Across three pre-registered experiments (N=1,650) and an archival analysis of S&P 1500 corporate board data, we show that as a homogeneous group increases in size, decision-makers are more likely to add members who increase the group’s demographic diversity. This effect is partially mediated by the group’s perceived diversity. This work increases our understanding of how diversity is perceived and helps explain why large corporate boards without women or racial minorities are significantly rarer than expected by chance.