The more the merrier or too many cooks spoil the pot? A meta-analytic examination of team size and team effectiveness

Scholars often implicitly assume that team size is associated with team effectiveness, but there is evidence of meaningful variability in this relationship that may correspond with competing theoretical perspectives. In particular, positive effect sizes between team size and team effectiveness correspond with a human capital perspective; negative effect sizes correspond with a process loss perspective. This study tests a series of contextual moderators aimed at evaluating these competing theories. Our team-level meta-analysis (k = 208, N = 21 435) confirmed a null, yet extremely variable, relationship (rho$$ \hat{\uprho} $$ = .00) between team size and team task performance. Importantly, we find support for both theoretical perspectives through our moderator analyses, with team size being more strongly associated with performance when tasks are complex, consistent with a human capital perspective, but less strongly associated with performance when high coordination requirements are coupled with low task complexity, consistent with a process loss perspective. Contrary to our expectations, the relationship between team size and team task performance did not vary as a function of national culture. Meta-analyses of associations between team size and other team-level effectiveness indicators revealed connections with deviant behaviors (rho$$ \hat{\uprho} $$ = .17) and passive withdrawal behaviors (rho$$ \hat{\uprho} $$ = .13) and a small negative relationship (rho$$ \hat{\uprho} $$ = -.04) with team attitudes. We discuss the theoretical and practical implications of these findings.