Quasi-Experimental Estimates of the Effects of a Preschool Intervention

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Abstract
Estimates of program effects from a compensatory preschool intervention were investigated using several contemporary techniques of bias reduction. These included econometric simulta neous modeling, latent-variable structural modeling, and ordinary least squares regression. These techniques were applied to longitudinal data from Chicago's Child Parent Center preschool program, a Head Start-type intervention. Analyses of 806 Black children followed from kindergarten to Grade 6 indicated that the techniques, by and large, produced similar estimates of program impact on school achievement test scores. Effect sizes ranged from .43 to .67 at school entry to .24 to .30 at Grade 6 (7 years postprogram). These findings were robust across different model specifications and similar to those of randomized studies. The only differences among methods occurred at Grade 3. Findings suggest that different quasi-experi mental estimation methods that attempt to control for selection bias can generate similar estimates of the effects of an educational treatment.