Do Charters Perform Better Because They Cherry Pick Students?

Do charter schools perform better because as the education establishment asserts they “cherry pick” the best students leaving the “normal” schools with the dregs. This is further evidence that there is a deeply ingrained belief (taught in education schools) that demographics are the determining factor in student achievement and that the schools and teachers have a very small impact on that achievement. E.D. Hirsch Jr. states it well in his book “The Knowledge Deficit.” “Determinism—the belief that demographics determine ability to learn. “Determinism is nonetheless a flawed and dismal theory, which, while conveniently exculpating the schools, undermines the founding principles of democratic education.” Hundreds (perhaps even thousands by now) of studies have shown that the schools and teachers do have the dominant effect on student achievement. Mortimore and Sammons (September 1987). New Evidence on Effective Elementary Schools. Educational Leadership, 45. found that in math the teacher had up to 10 times the impact of student background (demographics) in math and up to 6 times in reading. Of course if the schools are working with a strong self-fulfilling prophecy in place then the teacher impact is low.

New research on charter school performance versus the mainline schools has been done by Caroline Hoxby, a Stanford economist found a new way to examine the alleged cherry picking bias claim. The results come out in favor of charter school performance being real and not a cherry picking phenomenon. This was reported in the Wall Street Journal of Sept. 24, 2009. “Hoxby’s 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.” The technique she used took advantage of the fact that more kids apply than there is room for in the charter schools. The students are selected by a lottery so that no pre-selection bias is present. Thus comparing achievement between the charter schools and the population of students who applied but didn’t win the lottery is a valid way to see the impact of the charter schools on the achievement of that population.

“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.”

Charter students are also shrinking the learning gap between low-income minorities and more affluent whites. "On average," the report concludes, "a student who attended a charter school for all of the grades kindergarten through eight would close about 86% of the 'Scarsdale-Harlem achievement gap' in math and 66% of the achievement gap in English."

Hoxby used the same approach to study Chicago charters and found they performed even better than those in NY. Other researchers using the same approach have seen similar results in Boston.

Thus, another bogus reason needs to removed from those used by the mainline schools to make excuses for inexcusable performance.