Elizabeth U. Cascio and Diane Whitmore Schanzenbach. 2013.The impacts of expanding access to high-quality preschool education. Working Paper 19735. National Bureau of Economic Research
Abstract:President Obama’s “Preschool for All” initiative calls for dramatic increases in the number of 4 year olds enrolled in public preschool programs and in the quality of these programs nationwide. The proposed program shares many characteristics with the universal preschools that have been offered in Georgia and Oklahoma since the 1990s. This study draws together data from multiple sources to estimate the impacts of these “model” state programs on preschool enrollment and a broad set of family and child outcomes. We find that the state programs have increased the preschool enrollment rates of children from lower- and higher-income families alike. For lower-income families, our findings also suggest that the programs have increased the amount of time mothers and children spend together on activities such as reading, the chances that mothers work, and children’s test performance as late as eighth grade. For higher-income families, however, we find that the programs have shifted children from private to public preschools, resulting in less of an impact on overall enrollment but a reduction in childcare expenses, and have had no positive effect on children’s later test scores.
数据来源：国家早期教育研究所National Institute for Early Education Research (NIEER)
Conclusion:President Obama’s $75 billion “Preschool for All” initiative calls for dramatic increase sin the number of 4 year olds in public preschool programs and in the quality of these programs across the nation. This proposal shares—and other proposals likely to follow will share—many characteristics with the state-funded preschool programs Georgia and Oklahoma, which both meet high-quality benchmarks and are accessible to all children. We estimate the impacts of these “model” programs on a variety of child and family outcomes using difference-in-difference frameworks. Our findings suggest sharply different impacts for children from across the income distribution, which is not surprising when one recognizes that the impact of attending a high-quality public preschool depends crucially on what the child would have been doing in the absence of the program.
For lower-SES children, we find evidence of increases in math scores that may be sustained through eighth grade. The increases may be working through multiple channels. First, children are likely to switch from not attending preschool to attending a high-quality public preschool when a universal program is introduced. Moreover, we find suggestive evidence that although they spend less time overall in the presence of their mothers, they spend more time actively engaging in activities such as playing and reading with them. We also find suggestive evidence that their mothers become employed. For higher-SES children, we find no positive impacts on student achievement. These children are much less likely to be moved on the extensive margin of preschool enrollment, and instead are more likely to switch from private to public preschool in response to the program. We also find suggestive evidence that some families are able to substantially reduce their spending on private preschool and childcare in response to the program, freeing these resources up for other purposes.
This pattern of results raises the question of whether the proposal design could be altered to obtain the same positive impacts without inducing as much crowd-out. Could a targeted program meet these goals more efficiently? The findings of rapid and complete fadeout in test score effects in recent randomized controlled trials of Head Start (Puma et al., 2012) and Tennessee’s targeted voluntary preschool program (Lipsey et al., 2013b) suggest that targeted programs today might not induce such gains. One possible explanation is that the test score impacts of universal programs rely on peer effects in preschool classrooms. Indeed, universal programs might be “high quality” not because they meet specific quality benchmarks, but rather because of improvements in the classroom environment from the presence of higher-SES children. We cannot rule out this possibility, and we think it is an important question for future research.
That said, while the Georgia and Oklahoma programs share a number of features with the preschool programs proposed under the Obama plan, there are several reasons to be cautious in generalizing our findings. First, and most importantly, the Obama plan gives states discretion over whether and how much to charge middle-class families for access to the public programs. The more that states charge middle-class families, the less substitution away from private programs there is likely to be. Second, while it has been the focus of our analysis, universal preschool is not all that there is to the “Preschool for All” initiative. For example, it also calls for increases in Head Start enrollment among 3 year olds, which affect the success of universal preschool in ways that we have not been able to measure. On the other hand, our suggestion that the programs in Georgia and Oklahoma have had some lasting impacts on the human capital of lower-SES children might have nothing to do with the quality benchmarks emphasized in the Obama plan. We have estimated the reduced-form impacts of these programs, and the mechanisms at work are not completely clear. The available data have also limited our analysis in important ways that might be rectified in future research.