Requiring private schools that receive public money to report student test scores improves academic achievement and ultimately enhances school choice, a Michigan State University scholar argues. In a pioneering study, Joshua Cowen and colleagues found that voucher（收据，证人） schools in Milwaukee saw a large jump in math and reading scores the year after a new law required them to release the results. During the four years before the law was enacted, math and reading scores declined or remained stagnant.

The study, which appears in the journal Educational Evaluation and Policy Analysis, is the first to provide scientific evidence that accountability measures can improve test scores in private schools that serve students through tax-funded vouchers.

"School choice is enhanced when voucher schools or other alternatives supported on the public dime report more rather than less information," said Cowen, associate professor of education policy and teacher education. "It's a victory for public oversight as well."

Thirteen states and the District of Columbia use school vouchers. Other states, including Michigan, have laws allowing for charter schools, which are public schools that operate independently.

While voucher and charter schools have varying levels of accountability, many school-choice proponents（支持者） are opposed to the public disclosure of test scores, arguing that competition alone should be enough to weed out poor-performing schools.

The voucher program is targeted toward poor students in big cities. Cowen believes there is a role for school choice to play in these urban areas, where many students are desperate for high quality schools.

But at the same time, he said families should have as much information as possible to make their educational decisions.

"Without public reporting of academic results, how will the parents of these students know which private schools are worth choosing and which should be avoided?" Cowen said. "If we ask them to trust that the market will work, why not let them verify it?"

The study looked at state standardized tests in Milwaukee's voucher program from 2006 to 2010. The program is the oldest and one of the largest school voucher systems in the nation, serving 21,000 students, or nearly a fifth of Milwaukee's K-12 population.

A Wisconsin law requiring public reporting of test scores from voucher schools went into effect during the last year of the study, 2010, giving researchers a rare look at private-school test scores both before and after the accountability mandate（授权，命令）.

The test scores went up pretty much across the board, Cowen said, though it's not clear what fueled the improvement. It could be that education truly improved or perhaps that voucher schools were simply "teaching to the test," he said.