Julia Sass Rubin, a professor of public policy in New Jersey, took a close look at the CREDO study of charter schools and made a startling discovery: the press release misrepresents the findings of the study.

It recognized the dramatic demographic differences between the students in public schools and in charter schools (“the traditional public schools it looked at served four and a half times as many students with Limited English Proficiency and one and a half times as many special-needs students as did the charter schools”) but ignored the severity of students’ disability or language difficulty.

This is an excerpt from her longer analysis. Rubin wrote:

“The CREDO press release claimed that “New Jersey charter public schools significantly outperform their district school peers.” However, this is not even remotely what the CREDO study found.

“First, the CREDO study looked at only about half of New Jersey’s charter schools (46 out of 86).
Second, the study excluded another quarter of the state’s charter school students (23 percent), particularly those from groups that score lower on standardized test scores (students who have to repeat a grade, students with special needs, and students with limited knowledge of English).
Third, the study did not include students who had left charter schools. This is especially problematic given the significant attrition levels at the highest scoring charter schools, with the most academically challenged students the most likely to leave.

“So what did the CREDO study find about the performance of the remaining students?

“The vast majority of charter school students performed worse or at the same level as students in the traditional public schools from which they came (70 percent lower or same in math and 60 percent lower or same in reading).

“The charter school students who performed better were located almost exclusively in Newark, while charter school students in other cities and rural areas consistently and significantly underperformed their traditional public school peers.

“The charter school students who performed better did so only for their first two years at the charter school, while their third year performance was actually worse than their traditional public school counterparts.

“In other words, the study looked at a limited sample of charter school students, excluding those most likely to be academically challenged, and still found that only a minority of those students outperformed their traditional public school counterparts, and only for some of the years studied.

“Which brings us back to the first question: How can an institution that claims to be academically objective put out a press release that is so misleading about the study’s findings?”