Assessing Harlem Children's Zone

...or not.
Interesting piece pointing out the lack of assessment of the Harlem Children's Zone, which, as I've pointed out before, is now being copied nationwide.

You have set a 65 percent "tipping point" as a universal goal for your programs, after which you think success becomes inevitable. How did you determine that 65 percent was the tipping point?

Why that number? Why that number and not 70, 80 percent? There's no science there. You don't go look up, find the tipping point of a poor community—there's no science there. You take your best educated guess. …