Students attend class at a charter school in New Orleans in 2015. More than half of Louisiana’s public schools are low-performing.

Louisiana’s private school voucher program – the fifth-largest in the country – is having a negative impact on students who use the vouchers to enroll in private school, a mounting body of evidence shows.

“Most striking, we find strong and consistent evidence that students using a [voucher] performed significantly worse in math after using their scholarship to attend private schools,” said Patrick Wolf, the lead author for a series of studies published Monday by the university’s School Choice Demonstration Project and Tulane University’s Education Research Alliance for New Orleans.