D.C. Voucher Study Offers Little Support for Continuing Program
May 21, 2009

Contact: Teri Battaglieri (248) 444-7071;
Martin Carnoy (650) 856-7722;

EAST LANSING, MI (May 21, 2009)—A recent evaluation report on Washington, D.C.’s voucher program finds that after three years voucher students showed modestly higher reading scores, but no significant difference in math scores when compared with a control group of students who didn’t get vouchers. A new review of the report, however, points out that any such effect is modest and provides little support for vouchers as a solution to the educational problems in D.C.  

The report, Evaluation of the DC Opportunity Scholarship Program: Impacts After Three Years, was co-published by the University of Arkansas’ School Choice Demonstration Project and by the Institute of Educational Sciences at the National Center for Educational Evaluation and Regional Assistance. It was reviewed for the Think Twice think tank review project by Martin Carnoy of Stanford University, an economist and expert in voucher research.

The D.C. program offers vouchers to low-income students in public schools, helping them attend one of about 60 participating private schools. The study analyzes reading and math achievement test scores of randomly selected applicants who were offered a $7,500 voucher during the first two years of the program, comparing these students with a control group of other applicants who were not offered vouchers.

The study concluded that, after three years, students who used vouchers scored 5.27  points, or one-sixth of a standard deviation, higher than those who stayed in public schools on achievement tests in reading—a statistically significant difference—and less than 1 point higher in math, which was not statistically significant. However, Carnoy points out that analyses of subgroups of these students show that any positive voucher effect on reading was concentrated among female middle school students with higher initial reading scores. Moreover, while Congress created the voucher program primarily to benefit students attending D.C. schools designated as “needing improvement”—the study found that the voucher effect was focused on students who had not attended those schools.

Carnoy summarizes the findings emphasized in the report as follows: “Sending low-income students to existing, predominantly religious (and even predominantly Catholic), small (average size, 265 students) private schools with small class sizes (average student-teacher ratio, 10.3 students) can modestly increase these students’ achievement (in reading but not mathematics) and results in greater parent satisfaction with their children’s school.”

However, closer inspection of the results, Carnoy writes, suggests that the results showing a positive effect from vouchers are primarily due to the first cohort of students enrolled in the program. By the second year, available private school seating was reduced. And, due to research design limitations, the first cohort did not include elementary-level students – a group that, in the second cohort, did not appear to have benefited. Carnoy faults the study for not offering any detailed analysis of differences among the two cohorts of students enrolled in the program, which might shed light on factors other than vouchers influencing the results.

Find Martin Carnoy’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.


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