Do private school vouchers help? New study offers data.

African-American students who used private school vouchers were 24 percent more likely to go on to college than blacks in a control group, the study says. But debate over vouchers has followed.

A new study suggests that private school vouchers can have a positive impact on the rate at which African-American students attend college.

The study takes a rare long-term view of vouchers, which are often studied for shorter-term effects such as gains on test scores.

“We want to have our students college-ready, and to learn that for African-American students, this is a way of improving their chances of being college-ready ... is a really important finding,” says voucher advocate Paul Peterson, a Harvard professor and director of the university’s Program on Education Policy and Governance, which published the study with the Brookings Institution on Thursday.

The randomized experiment compared about 1,300 students who won a New York City lottery in the late 1990s for privately funded vouchers with a control group that applied for but did not win the lottery.

Tracking them until 2011, it found no significant effect in the overall group, but African-American students who used the vouchers to attend private schools were 24 percent more likely to go on to college than African-Americans in the control group. For private four-year college attendance, the increase was 58 percent.

Because vouchers are such a politicized issue, the study has stirred up a variety of reactions. Voucher proponents cite it as another reason to support programs that provide public dollars to low-income parents who want to send their children to private or parochial schools. Groups opposed to vouchers, as well as some academic researchers, point to the limited scope of the study and raise questions about the methodology.

“Pundits may dismiss vouchers, but African-American parents know they work, and strong scientific data prove they work,” said Robert Enlow, president of the Friedman Foundation for Educational Choice in Indianapolis, in a statement.

“The grandiose statements made in the executive summary are not substantiated by the data,” countered Anne Bryant, executive director of the National School Boards Association, in a statement. The NSBA opposes publicly funded vouchers for private schools.

The study doesn’t track what happens to people who left the voucher program, nor does it effectively isolate the impact of private school or school choice, NSBA contends.

Expanding voucher programs wouldn’t necessarily yield the same kinds of results because including more low-income students in private schools changes the social composition of schools – the “peer effect” on student achievement when there are more middle- or upper-income students, says Christopher Lubienski, an education policy professor at the University of Illinois at Urbana-Champaign.

While the study authors acknowledge that near the end of the report, he says, “it would be better to control for that [peer effect] in the study.”

Research as a whole indicates “there doesn’t appear to be much of an impact” on student success from school vouchers, Professor Lubienski says.

During this presidential election season, school choice is one education issue Mitt Romney is trying to use to appeal to the Republican base. He cites strong results from a voucher program in the District of Columbia that President Obama did not propose to continue funding in his 2013 budget.

Republicans make a moral argument that Mr. Obama is standing in the way of school choice for poor African-Americans, but a study showed the program didn’t have a major impact, Lubienski says.

In the 2012 Phi Delta Kappa/Gallup poll on education, 44 percent of Americans say they favor allowing students to choose a private school at public expense. Since 1993, such support has fluctuated between 24 percent and 46 percent.

Thursday’s study suggests that vouchers could be a cost-effective policy option when compared with other education-related spending. The vouchers were for $1,400 a year and were used for an average length of 2.6 years. The study contrasts that with the $12,000 per-pupil price tag of a Tennessee program to reduce class size – which was found to increase African-American college enrollment by 19 percent.

The authors – Professor Peterson and Matthew Chingos, a fellow at Brookings’s Brown Center on Education Policy – also interpret a study on the impact of having a more effective teacher, and they say their voucher study yields better results.