Strengthening Benefit-Cost Analysis for Early Childhood Interventions Workshop Summary (2009) / Chapter Skim
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2 Evaluation
2 Evaluation
Pages 9-16
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From page 9... ...
Ludwig discussed some of the methodological challenges that arise when randomized experiments deviate from the ideal design, as they often do in the real world. He also discussed alternative options for estimating causal relationships that can be used when strictly randomized experiments are not feasible.
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From page 10... ...
Ludwig pointed out that although the response rates in the Head Start study have been good, particularly considering that the program population is very disadvantaged, it is important to ask whether the level of attrition is sufficient to raise cautions about the causal inferences the study was designed to support. There are several ways to approach that question.
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From page 11... ...
The cleanest solution to that problem is to examine outcomes for everyone randomly assigned to the treatment group, regardless of whether they participate in Head Start -- the "intent-to-treat" group. This approach will make it possible to identify the effect of being offered Head Start, but it will lead to an underestimate of the effects of actually participating in Head Start (because some children assigned to the treatment group do not participate)
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From page 12... ...
Ludwig said that using the approach suggested by LaLonde to analyze the experimental data from the federal government's recent Head Start study would provide valuable information about the potential biases that may affect nonexperimental estimates in the early childhood education area. One particularly promising nonexperimental approach to estimating effects is based on the idea that "nature does not make jumps," so that unusual patterns in program data are likely to indicate an effect.
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From page 13... ...
David Deming focused his presentation on multiple inference adjustments, which are strategies for accurately identifying individual effects in the context of an analysis that covers multiple outcomes and multiple groups. There are two general approaches to this problem, Deming explained.
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Different analytical approaches may yield different results, as happened, for example, with two different benefit-cost studies of the Perry Preschool Project, which produced vary ing results. One found larger effects for girls, and the other found larger effects for boys.
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From page 15... ...
. The Perry Preschool Project The Perry Preschool Project was a study of the effects of high-quality care and education on low-income 3- and 4-year-olds conducted by the HighScope educational research Foundation.
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From page 16... ...
We are giving pretty broad latitude to the possibility that there are meaningful effects that aren't passing the statistical tests."
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