Scholars Spar Over Research Methods Used to Evaluate Charters

The authors of a recent national study that found students in regular public schools outperforming their charter school peers are rebutting criticism that their research suffered from a “serious mathematical mistake” that negatively skewed the results.

In a memorandum posted online last week, researchers from the Center for Research on Education Outcomes, or CREDO, at Stanford University responded to criticism made last month by their Stanford colleague Caroline M. Hoxby. Ms. Hoxby, an economics professor, issued a memo critiquing the CREDO study in tandem with results from her own study of charter schools in New York City.

That study showed that charter schools in the city were having the opposite effect on their students’ achievement as the CREDO researchers found. Compared with their public school counterparts, Ms. Hoxby found, students in charter schools made more progress in closing achievement gaps with better-off peers in the suburbs. ( "N.Y.C. Charters Found to Close Gaps," ...