What I make of that statement is that statisticians can make numbers say ANYTHING they want them to say!
Some vouchers only go to low income students. Some sample groups are very small. NONE of them offer anywhere NEAR the dollar amount that public schools get of public money.
According to this link
http://www.greatschools.org/gk/articles ... -vouchers/the LARGEST school voucher gives 5000/year. The public school kids in our district each cost 12000/year. In our state (Ohio) the money is ONLY given to kids who come from "failing" schools, and are financially disadvantaged. So, the state ruins them, then complains because the inadequately small voucher can't fix it.
So, you pay less than half the money, only give it to small, disadvantaged sample, and compare results as if it were an even playing field.
NEVER EVER EVER trust an article that gives "study results" without telling you how and by whom the study was conducted. And never trust the New York Times