The fight against poverty produces great programs but disappointing results. You go visit an inner-city school, job-training program or community youth center and you meet incredible people doing wonderful things. Then you look at the results from the serious evaluations and you find that these inspiring places are only producing incremental gains.

That’s why I was startled when I received an e-mail message from Roland Fryer, a meticulous Harvard economist. It included this sentence: “The attached study has changed my life as a scientist.”

Fryer and his colleague Will Dobbie have just finished a rigorous assessment of the charter schools operated by the Harlem Children’s Zone. They compared students in these schools to students in New York City as a whole and to comparable students who entered the lottery to get into the Harlem Children’s Zone schools, but weren’t selected.

They found that the Harlem Children’s Zone schools produced “enormous” gains. The typical student entered the charter middle school, Promise Academy, in sixth grade and scored in the 39th percentile among New York City students in math. By the eighth grade, the typical student in the school was in the 74th percentile. The typical student entered the school scoring in the 39th percentile in English Language Arts (verbal ability). By eighth grade, the typical student was in the 53rd percentile.