Using kindergarten lottery outcomes that determine which kids get into the most sought-after schools, they are able to compare the outcomes of those who win the lottery versus those who lose. The students who win the lotteries go to “better” schools and have “better” peers, but they don’t have better outcomes.
I've had real qualms about many school choice programs as I've seen them in action.
My first exposure was the basic public/parochial school split -- and it only seemed fair that Catholic families should get the money they pay in taxes for schools back to help educate their kids.
But, since then, I've seen so many bad schools operating as alternatives (and some really good ones too). But that essay, above, explained the hole in the logic I had not understood before.
I've got a lot more thinking to do, I obviously have a lot I still do not know, but this is one piece of the puzzle.