Evaluates empirical studies on child development. Suggests that most such research consists of studies of a priori, nonempirical, logical relations between concepts, whose definitions guarantee the relationship studied. Argues that hypotheses are empirical if variables involved are semantically and logically independent. Research that is not based…

Comments on the ideas espoused by Smedslund (PS 522 552) in this issue. Agrees to the idea of spending more intellectual energy in distinguishing between a priori and empirical hypotheses but emphasizes that concepts are not always accurate reflections of reality and that even empirical disconfirmation of an a priori hypothesis sometimes can…

This final report of the National Day Care Study (NDCS), Volume IV-A, contains three papers that help to set a context for interpreting overall study results. "Research Issues in Day Care, A Focused Review of the Literature" focuses on effects of group care and regulatable characteristics of the day care environment. The second paper,…