The study documenting the superior test scores of students in New York City Charter Schools, released earlier this week, should put the final nail in a long-held, shopworn attack by charter school opponents - that charter schools "cream" students from more "motivated" parents who enroll them.

We always knew these were canards.

Professor Caroline Hoxby of Stanford, and her co-authors Jenny Kang from the National Bureau of Economic Research and Sonali Murarka from the Wharton School at U-Penn, demonstrate conclusively what charter school operators have always known: charter schools tend to get a higher percentage of minority students and from lower-income households than the respective district average.

More significantly, this study, "How New York City's Charter Schools Affect Achievement," went the extra mile in comparing charter student test scores with those of district students that previously applied for admission to a charter school but were not selected through the lottery process, thus "lotteried out." The results are that charter students scored higher on the state exams compared to those students who were "lotteried out".

So, all together now: There no "creaming" going on, after all. Furthermore, the parents of those higher-scoring students were no more motivated in getting their child enrolled than the parents whose children got a higher lottery number and had to remain in the district. This comparison is the most scientific and reliable a researcher can make.

Again, charter school operators and proponents have always known this to be true and have said so. But that never stopped opponents of charter schools from dusting off their 1990's talking points to continuously try and discredit higher test scores in charter schools.

Today's Wall Street Journal includes an editorial highlighting this important finding (here) that should once and for all destroy the "creaming" and "motivated parents" arguments from charter school opponents.

Narrowing the Achievement Gap
As a result of charter school success, the study shows them significantly narrowing the achievement gap between urban and suburban districts in English and math -- a gap that also is largely racial. We already have seen this trend where charter schools each year were narrowing this gap to the point of now having similar percentages of students meeting state standards as suburban school districts, more so in mathematics. This study, therefore, represents more definitive evidence of that favorable and encouraging trend.

Peter Murphy
for The Chalkboard