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One possible explanation for the negative effects of Louisiana's voucher program is that there was adverse selection of schools into the program. That is, schools that did join the program may have been relatively poor performers.
It is not clear why adverse selection might have occurred. One possibility is that schools enrolled that would otherwise have had difficulty retaining students and needed cash flow from vouchers (Walters, 2016). The question of why this adverse selection that the program included regulations requiring participating schools Another possibility, favored by school choice advocates, is that some schools did not participate because of the burden of regulation (Forster, 2016). Under the Louisiana program, participating schools had toadminister state testing and to be were subject to inspections by public officials (Forster, 2016). As a result of these regulations, many private schools that may have potentially participated in the program perhaps feared additional regulations that may be imposed by the program and opted not to participate. .
Milwaukee
Milwaukee is an important program because it was the first publicly funded voucher program in the country, established in 1990 (Rouse, 1997). In interpreting the Milwaukee results, it is important to note that the Milwaukee study was relatively small, with a few hundred students, and as a result the program's effect is highly uncertain and could be much smaller or larger than the point estimate. The forest plot indicates this by showing Milwaukee with a wide confidence interval. Because of this, Milwaukee gets relatively little weight in the US average (Shakeel et al., 2016).
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