Troy LaRaviere, head of the Chicago Principals’ Association, writes that school officials adjusted the scores of Chicago charter schools to make it appear that they made bigger gains than originally reported.

The original data showed that students in public schools were. Performing better than their peers in charter school.

(Read Peter Greene here on this shenanigan.)

This is a small part of Laraviere’s findings:

“Our findings were published in a Chicago Sun-Times Op-Ed. In addition, the Sun-Times published its own independent analysis, which affirmed our findings. Our analysis was based on a file containing the school level results of the Northwest Evaluation Association (NWEA) Measures of Academic Progress (MAP) assessment. This file was released by the CPS Office of Accountability in early August. That original file is no longer available on the Office of Accountability website. At some point between the publication of our findings and the release of school ratings, CPS removed the original file containing school growth data and replaced it with a different version. There are no indications or acknowledgements on the site that the data in the file has been changed.

“Fortunately, we saved the original version.

“An analysis of both versions indicates massive changes were made to the student growth data for charter schools at some point during the last few months as CPS delayed the release of school quality ratings.

“Findings

“We found these changes led to certain schools appearing to have greater academic growth by lowering the average pretest scores while leaving the posttest scores as they were. For other schools, the changes raised the pretest scores and once again left the posttest scores as they were, giving the impression of less student growth.

“The changes were made to the data for nearly every charter school while affecting less than 20 public schools. Charter school scores were changed by more than 50 percentile points in some cases while most of the public school changes were 2 points or less.”

The Chicago Sun-Times reported the story. LaRaviere said to the Sun-Times:

““In a system based on ‘choice,’ parents and other stakeholders must be provided with accurate indicators of school quality. [CPS’ ratings system] cannot serve this purpose if there are clouds of suspicion about tampering with the data used to determine these ratings,” LaRaviere said in an email.”