Matt Barnum reports that new research from Louisiana shows that the negative effects of vouchers persist over time. 

There used to be a belief that the negative effects were temporary, but apparently the voucher students do not bounce back, as voucher proponents hoped.

New research on a closely watched school voucher program finds that it hurts students’ math test scores — and that those scores don’t bounce back, even years later.

That’s the grim conclusion of the latest study, released Tuesday, looking at Louisiana students who used a voucher to attend a private school. It echoes research out of Indiana, Ohio, and Washington, D.C. showing that vouchers reduce students’ math test scores and keep them down for two years or more.

Together, they rebut some initial research suggesting that the declines in test scores would be short-lived, diminishing a common talking point for voucher proponents.

“While the early research was somewhat mixed … it is striking how consistent these recent results are,” said Joe Waddington, a University of Kentucky professor who has studied Indiana’s voucher program. “We’ve started to see persistent negative effects of receiving a voucher on student math achievement.”

The state’s voucher program also didn’t improve students’ chances of enrolling in college.

The results may influence local and national debates. Secretary of Education Betsy DeVos is working to drum up support for a proposed federal tax credit program that could help parents pay private-school tuition, and Tennessee lawmakers are debating whether to create a voucher-like program of their own.

If past history is a guide, Betsy DeVos will dismiss the research, as will Tennessee Governor Bill Lee. They want vouchers regardless of their impact on students.