Making the Most of Small Effects


Ross A. Thompson, Department of Psychology, University of California, Davis, One Shields Ave., Davis, CA 95616, USA. Email:


The idea that classroom social ecologies are shaped by the aggregate effects of peers’ prior care experiences is provocative, even though the evidence is weak that this explains the small and diminishing effect of childcare experience in the National Institute of Child Health and Human Development study. Small effects may indeed be small effects, but students of early development should attend to the potential importance of group-level influences on social and cognitive growth.