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February 23, 2009
By Greg Forster
Jay P. Greene’s Blog
On Friday, the Friedman Foundation released my new report, "A Win-Win Solution: The Empirical Evidence on How Vouchers Affect Public Schools." It goes over all the available empirical evidence on . . . well, on how vouchers affect public schools. Here's the supercool graphic: 
Worth a thousand words, isn't it? I mean, at what point are we allowed to say that people are either lying, or have been hoodwinked by other people's lies, when they say that the research doesn't support a positive impact from vouchers on public schools? There's always room for more research. What would we all do with our time if there weren't? But on the question of what the research we now have says, the verdict is not in dispute. Here's the executive summary of the report: This report collects the results of all available empirical studies on how vouchers affect academic achievement in public schools. Contrary to the widespread claim that vouchers hurt public schools, it finds that the empirical evidence consistently supports the conclusion that vouchers improve public schools. No empirical study has ever found that vouchers had a negative impact on public schools. There are a variety of explanations for why vouchers might improve public schools, the most important being that competition from vouchers introduces healthy incentives for public schools to improve. The report also considers several alternative explanations, besides the vouchers themselves, that might explain why public schools improve where vouchers are offered to their students. It concludes that none of these alternatives is consistent with the available evidence. Where these claims have been directly tested, the evidence has not borne them out. The only consistent explanation that accounts for all the data is that vouchers improve public schools. Key findings include: - A total of 17 empirical studies have examined how vouchers affect academic achievement in public schools. Of these studies, 16 find that vouchers improved public schools and one finds no visible impact. No empirical studies find that vouchers harm public schools.
- Vouchers can have a significant positive impact on public schools without necessarily producing visible changes in the overall performance of a large city's schools. The overall performance of a large school system is subject to countless different influences, and only careful study using sound scientific methods can isolate the impact of vouchers from all other factors so it can be accurately measured. Thus, the absence of dramatic "miracle" results in cities with voucher programs has no bearing on the question of whether vouchers have improved public schools; only scientific analysis can answer that question.
- Every empirical study ever conducted in Milwaukee, Florida, Ohio, Texas, Maine and Vermont finds that voucher programs in those places improved public schools.
- The single study conducted in Washington D.C. is the only study that found no visible impact from vouchers. This is not surprising, since the D.C. voucher program is the only one designed to shield public schools from the impact of competition. Thus, the D.C. study does not detract from the research consensus in favor of a positive effect from voucher competition.
- Alternative explanations such as "stigma effect" and "regression to the mean" do not account for the positive effects identified in these studies. When these alternative explanations have been evaluated empirically, the evidence has not supported them.
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