Do vouchers mostly help kids toward the top of the achievement distribution or kids towards the bottom? Or is one group helped and one group hurt? (We’re talking about what happens to the specific kids who get vouchers, not whether vouchers are good for society at large.) Maybe all students gain. Or maybe some gain and some lose such the net effect is zero.
Marianne Bitler and colleagues looked at a school voucher program in New York City that offered $1,400 vouchers (so the vouchers weren’t huge) to low-income kids. Most voucher recipients made use of the extra money to attend private schools.
Since the vouchers were given out by lottery, Bitler et. al. can compare what happens to winners and losers. In particular they can look at what happened to kids who started near the bottom of the achievement distribution and what happened to kids who started near the top. Here’s one picture from the paper. The horizontal axis reads left-to-right “initially low” to “initially high.” The vertical position of the solid line measures the effect of receiving the voucher.
Quantile treatment effect estimates of the impact of a voucher offer on math National Percentile Rankings at baseline
The message is that the solid line is roughly at zero. So the voucher program had no effect at the top, no effect at the bottom. And for that matter no effect in the middle either.
Wednesday we’ll look at an analogous study of Head Start with somewhat different results.