May 18, 2009

Review concludes that positive tests-score effects of voucher competition on Milwaukee public schools are very small at best

Contact: Gregory Camilli (732) 932-7496;

EAST LANSING, MI (May 18, 2009)—A recent report contends that competition from Milwaukee’s private school voucher program for low-income families has benefited Milwaukee public schools. A Think Twice review of that report raises a number of questions about its statistical methods and concludes that any positive effect of competition is very small, if it exists at all.

The report, The Effect of Milwaukee’s Parental Choice Program on Student Achievement in Milwaukee Public Schools, was written for the School Choice Demonstration Project at the University of Arkansas. It was reviewed for the Think Twice think tank review project by Gregory Camilli of Rutgers University, an expert in the use of statistics and measurement in social science research.

Camilli points out that the largest competition benefit emphasized in the report was obtained with no controls, but also that these benefits were small from a practical perspective. Moreover, when statistical controls are used, no statistically or practically significant competition benefits were found. Those controls essentially account for whether there is in fact private school competition for a public school student (that is, the effects of grade and year are distinguished from the effect of competition).

Despite the questions Camilli raises about the report, he commends it for clearly and thoroughly presenting its findings and for presenting its methods and statistical models clearly.

Camilli concludes, “Before the results of this study can effectively inform the decision of whether to expand or reduce the size of the voucher program in Milwaukee, a number of issues need resolution. Most importantly, the use of uncontrolled estimates requires justification.”

Find Gregory Camilli’s review on the web at:

About The Think Twice Project
The Think Twice project provides the public, policy makers and the press with timely, academically sound reviews of selected think tank publications. It is a collaboration of the Education Policy Studies Laboratory at Arizona State University and the Education and the Public Interest Center at the University of Colorado at Boulder and is funded by the Great Lakes Center for Education Research and Practice.


The mission of the Great Lakes Center is to improve public education for all students in the Great Lakes region through the support and dissemination of high quality, academically sound research on education policy and practices.

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