ABSTRACT
The most persuasive evidence that early intervention might avert negative childhood outcomes is found in studies of normal birth weight children from socially disadvantaged populations. The rationale for the study was based on the demonstrated risks for both health and developmental dysfunction in low birthweight infants and the necessity to test the efficacy in this population of an early intervention model designed for normal birth weight children. Because this study was conducted as a randomized clinical trial, it was important, for statistical validity, to restrict the number of primary outcome measures. The effect size for an outcome measure is the difference between the means for the intervention and follow-up groups expressed in standard deviation units. The intervention may have helped the less-educated mothers become better informed about age-appropriate behaviors and consequently report fewer problems; it may have taught them more effective techniques for behavior management; or it may have altered the children's behavior.
