In the long-running debate over vouchers, a report issued Monday says voucher recipients in Louisiana bounced back from dismal scores initially in math and English.

After three years those students were on par with public school students who tried and failed to land the assistance, according to a report by the Education Research Alliance in New Orleans.

State Superintendent of Education John White said the result of the review offer lessons for liberals and conservatives alike. White was part of a 75-minute panel discussion Monday on the report hosted by the Urban Institute in Washington, D.C.

Vouchers are state aid for students from low-income families who attend troubled public schools to move to private schools at state expense.

Around 7,100 students get the aid, and 87 percent are African American students, according to the study.

Backers call the aid – officially the Louisiana Scholarship Program, or LSP – a way out of dead end public schools.

Opponents contend vouchers have failed to deliver on the promises of backers, and rob financially-strapped public schools of needed revenue.

The study follows an earlier review that said voucher recipients did "significantly worse" than their peers in the first year, and "slightly less negative" after year two.

The latest review said that, after three years in the program, voucher recipients were performing roughly the same as their public school peers in math and English/language arts, or ELA.

"The program had large negative effects on student performance in both ELA and math after one year that appear to improve over time," according to the report.

"By the third year, the performance of LSP scholarship users was statistically similar to their counterparts in both ELA and math," it says. The review compared how students who landed vouchers through a state lottery fared with those who tried and failed to qualify for the assistance, and then remained in public schools.

Average tuition is $4,925 per year at voucher schools compared to $8,500 in government aid for public school students.

Top stories in Baton Rouge in your inbox

Twice daily we'll send you the day's biggest headlines. Sign up today.

The report said students scoring in the bottom third in English showed statistically significant gains after three years with vouchers.

White said comparable performance by voucher and non-voucher students should give pause to liberals who focus on admissions and accountability, and conservatives who complain that over-regulation is hurting the program.

The real question, he said, is whether states are offering quality schools for disadvantaged students, and White said school choice helps advance that goal.

A school choice advocacy group, EdChoice, said the report shows "voucher students, like any other students in transition, need time to adjust to their new educational environments."

"These results should be a cautionary tale for anyone jumping to conclusions based on one or two years of data," EdChoice President and CEO Robert Enlow said in a statement.

Enlow said a study of four years of voucher data in Indiana showed that, after an initial drop in test scores, both the reading and math results showed sharp turnarounds. "The trend lines in both states are heading in the upward direction," he said.

In other areas, the Louisiana study said students with disabilities are less likely to receive special education services if they get vouchers.

In addition, voucher students identified with disabilities were more likely to later lose those designations than students in public schools, the report says. Whether private schools are under-identifying students with disabilities or public schools are over-identifying them is unclear.

The report also said private schools that take part in the program are disproportionately Roman Catholic, charge low tuition, have low enrollments and serve a high percentage of minority students.

Only 33 percent of private schools in Louisiana take part in the voucher program compared to 70 percent in Indiana, according to the study.

The group that did the report is based at Tulane University.

It is affiliated with a wide range of public school groups, including the Louisiana Association of Educators, Louisiana Association of Public Charter Schools as well as the Urban League of Greater New Orleans.

The state spends about $42 million per year on vouchers.

The program, which was originally limited to New Orleans, became statewide in 2012 after a push from then Gov. Bobby Jindal.

Follow Will Sentell on Twitter, @WillSentell.