January 31, 2016


When winners are losers: Private school vouchers in Louisiana (Susan M. Dynarski, 1/28/16, Brookings)

A voucher lottery provides an unusual opportunity to measure the effectiveness of private schools. The lottery serves as a randomized trial, which is the gold standard of research methods. Random selection means that lottery winners and losers are identical, on average, when they apply for the voucher. Any differences that emerge after the lottery can therefore be attributed to the private-school attendance of the winners.

The results were startling. The researchers, a team of economists from Berkeley, Duke, and the Massachusetts Institute of Technology, found that the scores of the lottery winners dropped precipitously in their first year of attending private school, compared to the performance of the lottery losers. The effects were very large: roughly a quarter of a standard deviation in math, social studies, and science. There were no effects on reading scores. On a per-year basis, these negative effects are as large as the positive effects that a similarly-designed study found for charter schools in Boston (the authors of the Louisiana study are my collaborators in the charter research).[v] 

It's possible that the students entering private schools simply had a difficult transition year, and that's why their scores plummeted. But similar studies in charter schools, as well as other voucher studies, have found no such negative, first-year effect. The only way to know if the effect is positive or negative in the long term is to continue to track these students (using administrative data) as they progress through school. The researchers say they hope to carry out this follow-up research, assuming that the state continues to make the necessary data available.

It's also possible, as the researchers speculate, that the private schools participating in the voucher program are of lower quality than other private schools in Louisiana. They note that the private schools participating in the program experienced sharp enrollment declines right before they joined the program, which may indicate that paying parents found these schools unsatisfactory. Private schools outside the voucher program saw no similar declines.

At the very least, the results suggest that the participating private schools need to provide far more support for voucher students when they enter. If the voucher students continue to perform poorly, Louisiana needs to overhaul the criteria used for including schools in the voucher program--or shut down the program altogether.

Any system of vouchers requires testing standards and closure of underperforming schools.

Posted by at January 31, 2016 12:14 PM