Establishing the Integrity of the Independent Variable in Early Intervention Programs

With the implementation of P.L. 99–457, early intervention programs are becoming more widespread; they are also being pressed to become more accountable. Persons evaluating early intervention programs have typically adopted outcome-oriented approaches focusing exclusively on measuring the dependent program variable (i.e., changes in student measures). This article highlights some of the problems inherent in these traditional approaches to program evaluation. A number of recommendations are offered for assessing the independent variable with the same methodological rigor that is typically reserved for measuring student outcomes in program evaluation studies. The implications of this shift in methodological approach are discussed in terms of improving the ability to replicate successful programs, design new ones with increased efficiency, and provide long-lasting support for early intervention.