A new working paper published by the National Bureau of Economic Research revealed how Louisiana’s school voucher program is actually harming children in low-income families. The paper, which was issued in December, showed that attending a private school participating in the Louisiana Scholarship Program would increase the likelihood of failing in math by a shocking 50 percent.

"Voucher effects for reading, science and social studies are also negative and large. The negative impacts of vouchers are consistent across income groups, geographic areas and private school characteristics, and are larger for younger children,” the researchers wrote.

Under the No Child Left Behind Act of 2001, school choice allows parents to send their child to the public or private school that best serves their needs. Many school choice advocates argue that students from wealthy families already have the benefit of these options because their families have more choices when selecting where to live and where to educate their children. Implementing school choice for all other students, advocates say, gives students from low-income families a shot at a better education.

But the working paper raises questions about the effects of school choice and Louisiana’s high-profile program. It found that sending poor students to LSP-participating private schools actually reduces academic achievement and lowers average test scores one year after program entry.

“These results suggest caution in the design of voucher systems aimed at expanding school choice for disadvantaged students,” researchers wrote. “Nonetheless, the evolution of choice behavior and program effects over time is an important question for future research.”

George W. Bush school choice President George W. Bush makes remarks on education reform and parental options in Washington in 2003. Photo: Luke Frazza/AFP/Getty Images

These findings, however, may not stop parents from wanting to send their children to private schools participating in the controversial program. “Parents may be willing to accept achievement losses in exchange for religious instruction or a change in peer environment,” researchers noted.

This is not the first time LSP has come under fire. The state released data in 2013 that showed at least 45 percent of students in the voucher program attended schools with performance scores in the D to F range of the state's grading scale. Louisiana released the scores several days after a federal judge ruled the U.S. Justice Department had the right to monitor the program to make sure it does not worsen racial segregation, the Times- Picayune in New Orleans reported at the time.

The LSP is a large, targeted voucher plan providing private school tuition payments for poor students attending low-performing public schools in the state. The program targets families with income below 250 percent of the poverty line and allocates seats at oversubscribed private schools by a random lottery.