Review praises report but warns about causal suggestion
Contact: Casey D. Cobb, (860) 486-0253; casey.cobb@uconn.edu
Nikki Rashada McCord, EPIC, (303) 735-5290; Nikki.McCord@colorado.edu
BOULDER, Colo. and TEMPE, Ariz. (March 31, 2010) -- A recent report from "School Choice Wisconsin" finds that students who attended private high schools under the Milwaukee voucher program had higher graduation rates than their Milwaukee Public Schools counterparts. A new Think Tank Review Project review praises the report as technically accurate and descriptively useful but notes that any real claims about whether the voucher program is actually causing higher graduation rates would depend on a much stronger research design.
The report, Graduation Rates for Choice and Public School Students in Milwaukee, 2003-2008, was written by John Robert Warren, a University of Minnesota sociologist. It was reviewed by Casey Cobb, director of the Center for Education Policy Analysis at the University of Connecticut's Neag School of Education.
Warren's report compares the graduation rates of a sample of students attending regular Milwaukee Public Schools (MPS) high schools with a sample of high school students enrolled in the Milwaukee Parental Choice Program, which pays for low-income families in MPS to send their children to private schools. Examining six years of data, it finds that voucher students' graduation rates exceeded those of MPS students in five of the six years.
"The methods used in the report are statistically precise and explained in very clear detail," Cobb writes in his review. For the most part, the data on graduation rates "represent reasonable estimates," he notes.
But one key assumption--that net migration in or out of the public and private school programs was zero--was not supported by any direct evidence, Cobb observes. This could present a source of bias, because net in-migration tends to bias a graduation rate figure upward, while net out-migration biases the figure downward.
More importantly, any claims that the voucher program causes higher graduation rates "must be based on stronger research designs." The report does acknowledge that limitation, and it directs readers to a forthcoming longitudinal study of the program that is not yet complete, Cobb notes. Yet then it undermines that caution by stating that, if the MPS graduation rate had equaled that of the choice program, 3,352 more MPS students would thus graduated. "Although mathematically accurate, such extrapolation invites causal inferences," which would mislead readers, Cobb concluded.
The Think Tank Review Project (http://thinktankreview.org), a collaborative project of University of Colorado at Boulder's Education and the Public Interest Center (EPIC) and the ASU Education Policy Research Unit (EPRU), provides the public, policy makers, and the press with timely, academically sound reviews of selected think tank publications. The project is made possible by funding from the Great Lakes Center for Education Research and Practice.
Find Casey Cobb's review on the web at:
http://epicpolicy.org/thinktank/review-graduation-rates-choice
Find Graduation rates for choice and public school students in Milwaukee, 2003-2008 by John Robert Warren on the web at http://www.schoolchoicewi.org/currdev/detail.cfm?id=309
CONTACT:
Casey D. Cobb, Director
Center for Education Policy Analysis
Neag School of Education
University of Connecticut
(860) 486-0253
casey.cobb@uconn.edu
Nikki Rashada McCord
Associate Director
Education & the Public Interest Center (EPIC)
University of Colorado at Boulder
(303) 735-5290
Nikki.McCord@colorado.edu
The Education and the Public Interest Center (EPIC) at the University of Colorado at Boulder and the Education Policy Research Unit (EPRU) at Arizona State University collaborate to produce policy briefs and think tank reviews. Our goal is to promote well-informed democratic deliberation about education policy by providing academic as well as non-academic audiences with useful information and high quality analyses.
Visit EPIC and EPRU at http://www.educationanalysis.org/
EPIC and EPRU are members of the Education Policy Alliance
(http://educationpolicyalliance.org).
###
**********