'Creaming" is the word critics of charter schools think ends the debate over education choice. The charge has long been that charters get better results by cherry-picking the best students from standard public schools. Caroline Hoxby, a Stanford economist, found a way to reliably examine this alleged bias, and the results are breakthrough news for charter advocates.
Her new study, "How New York City's Charter Schools Affect Achievement," shows that charter students, typically from more disadvantaged families in places like Harlem, perform almost as well as students in affluent suburbs like Scarsdale. Because there are more applicants than spaces, New York admits charter students with a lottery system. The study nullifies any self-selection bias by comparing students who attend charters only with those who applied for admission through the lottery, but did not get in. "Lottery-based studies," notes Ms. Hoxby, "are scientific and more reliable."
According to the study, the most comprehensive of its kind to date, New York charter applicants are more likely than the average New York family to be black, poor and living in homes with adults who possess fewer education credentials. But positive results already begin to emerge by the third grade: The average charter student is scoring 5.8 points higher than his lotteried-out peers in math and 5.3 points higher in English. In grades four through eight, the charter student jumps ahead by 5 more points each year in math and 3.6 points each year in English.
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