As growing numbers of Americans enter college, most colleges and universities have failed to ensure that those students will graduate, according to a study released yesterday by the Education Trust in Washington. Um, isn't it students' job to ensure they graduate? And given the pervasiveness of grade inflation it seems like universities have worked hard to hand out diplomas. Even so, many students fail to graduate on time: Only 63 percent of full-time college students at four-year colleges graduate within six years - a common yardstick for measuring graduation rates - the report said, and those rates have basically remained flat for 30 years. Graduation rates are especially low for minority students and those from low-income families, the trust said. Only 46 percent of black students, 47 percent of Latino students and 54 percent of low-income students graduate within six years. Might affirmative action have anything to do with this? Thomas Sowell and others have long claimed that affirmative action mismatches students and universities. So a student that might do just fine at a second-tier school gets into a top-tier school, but then fails to graduate. I assume this is a side effect of many preferential policies, including legacy students who get into Yale because dad went to Yale.