(Guest post by Greg Forster)
Potter cannot refute our findings, so she seeks to obfuscate them by carefully merging categories so as to define a “tie” as a loss.
Even to call the finding a “tie” is going too far. On net, which is all that counts, it was a win, not a tie. Big gains in public schools far outweighed the trivial negative effect in private schools. As I wrote:
When you’ve been in the education research business long enough, your eyes automatically roll by reflex whenever they read the words “mixed effect.” A mixed effect is a positive effect produced by a policy that the researcher doesn’t like.