Normally, when somebody hears about an evaluation of an education program, they reasonably assume the evaluation will tell them whether the program is working or not. When reading an evaluation report, policymakers, parents, and educators hope the evaluation will tell them if the program is helping the participating students. These seem like obvious, uncontroversial points.

On Monday, June 4, researchers from NC State released a working paper, An Impact Analysis of North Carolina’s Opportunity Scholarship Program on Student Achievement, which purports to be an evaluation of North Carolina’s largest private school voucher program. The authors enthusiastically publicized and distributed the report, making sure to provide advance copies to media organizations and a pro-voucher advocacy group. The report has been highlighted by all of the state’s major media outlets.

But there’s a problem: the report fails to tell us whether the Opportunity Scholarship program is working. The researchers’ efforts tell us nothing about whether accepting an Opportunity Scholarship will help or harm a student’s education.