A new report from the Friedman Foundation indicates that in 16 of 17 empirical studies on vouchers, the public schools also saw improvements.
(From: “A Win-Win Solution: The Empirical Evidence on How Vouchers Improve Public Schools”
(Note: A total of 17 studies are represented here; figures do not sum to 17 because some studies include findings on more than one program.)
The only study that showed no difference was for Washington, DC, where the voucher program includes rules that largely eliminate the potential competition aspects of vouchers for public schools.
Find the Friedman study here.