 The achievement gap closes faster in private schools not because white private school students lose ground with respect to white public school students as they move to higher grades, but because black private school students learn at a substantially higher rate than black public school students.Economist Derek Neal has found that black students attending urban private schools are far more likely to complete high school, gain admission to college, and complete college than similar students in urban public schools.Similarly, in a study comparing graduation rates of all Milwaukee public school students (of all income levels) with those of the low-income participants in the city's private school voucher program, Manhattan Institute Senior Fellow Jay Greene found the voucher students were more than one-and-a-half-times as likely to graduate as public school students.