Thursday, March 4, 2010

Experimental evaluation of Head Start

The official reports from a random assignment evaluation of Head Start were released in January; go here for the Executive Summary. Head Start is the federal pre-kindergarten program for disadvantaged children in the US. It dates back to the War on Poverty of the 1960s. It is one version of what you get when you try and scale up, but not spend too much money on, high intensity interventions like the famous Perry Preschool project in Ypsilanti that receives so much attention in the literature and whose long term experimental impact estimates are often held up as justification for expansion of programs such as Head Start.

I have not had a chance to read over this carefully but the results are pretty important. The study has three key design elements: (1) random assignment of access to Head Start; (2) the study sites are a random sample of Head Start sites around the country, which suggests strong external validity; and (3) a large amount of substitution into other types of center-based childcare and also a surprisingly large amount of control group cross-over into Head Start. There is also a non-trivial amount of treatment group dropout.

Factor (3) is important in interpreting the rather lackluster findings. The study is comparing the offer of Head Start access to the best alternative (which in some cases turns out to be a different Head Start center not in the experiment). The study is consistent with Head Start having a positive effect relative to the child staying home with the parents, but not much in the way of effects relative to the alternatives chosen by the parents in the absence of access to Head Start.

This study should slow the rush to spend large sums on these programs and hopefully will encourage a systematic program of research aimed at learning what types of early education programs have persistent impacts that cover their costs for this age group.

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