Effect size, practical importance, and social policy for children

Real decisions for real children are influenced by the papers developmental ists write, regardless of whether rye ever intended our payers to be used i n the policy arena. Yet most social scientists seldom analyze data in ways that are most useful to policymakers. The primary purpose of this paper is to share three ideas concerning how to evaluate the practical importance of a finding or set of findings. First, for research to be most useful not on ly in the policy arena but also more generally significance tests need to b e accompanied by effect size estimates. The practical importance of an effe ct size depends on the scientific context (i.e., measurement, design, and m ethod) as well as the empirical literature context. Second, researchers nee d to use all existing data when weighing in on a policy debate; here, meta- analyses are particularly useful. Finally, researchers need to be careful a bout embracing null or small findings, because effects may well be small du e to measurement problems alone, particularly early in the history of a res earch domain.