In an article for The Federalist, Dr. Will Flanders and Collin Roth of the Wisconsin Institute for Law & Liberty explain why recent voucher studies show students in Washington DC, Indiana, Louisiana, and Ohio falling behind their public school counterparts. It turns out, that effect of changing schools is temporary:

Dr. Patrick Wolf of the University of Arkansas and colleagues followed students randomly assigned to a school voucher in Louisiana via a lottery system. Such random assignment creates an experiment whereby the researchers can be far more certain that the effects they observe are due to the voucher program than other factors. In the first two years, Wolf and colleagues found negative effects on achievement in both math and language arts.

However, by the third year in the program, these negative effects have disappeared. The performance of students in the voucher program was found to be on par with their public school peers. This is in fact an improvement upon public schooling because it indicates the same level of achievement can be had at half the cost of public schools or less.

In Indiana, Dr. Mark Berends of Notre Dame and R. Joseph Waddington of the University of Kentucky found a similar pattern. Students entering the Indiana voucher program fell behind their public school peers initially, before equaling them (in the case of math) and surpassing them (in the case of English) by their fourth year.

The new results in Indiana and Louisiana are also consistent with the results of Milwaukee’s School Choice Demonstration Project that ended in 2012. That study of Milwaukee’s voucher program found insignificant differences among students in public schools and the voucher program. But the voucher students pulled ahead in English in the fourth year.

The significance of the pattern is still up for debate, but there is room for supposition. As with any student entering a new school, it is likely that newly minted voucher students undergo a period of adjustment. Differences in academic expectations, in school rules, and adjustments to a new social and academic environment may make it difficult for voucher students at first. But over time, these students adjust and increasingly thrive.