A researcher wants to study the effect of Denver’s reform policies. The superintendent has qualms.

Denver Superintendent Alex Marrero doesn’t want a University of Colorado Denver researcher to access student data to study the effects of the previous decade’s education reform policies.

Parker Baxter, who directs the University of Colorado Denver’s Center for Education Policy Analysis, was the lead author of a study released last year that found significant improvements in student test scores and graduation rates during the time Denver Public Schools was most invested in education reform strategies.

Two critiques of the study were that it didn’t isolate the effects of particular strategies, such as closing schools with persistently low test scores or opening new charter schools, and that it didn’t fully account for changes in the student population of Denver, which grew by some 20,000 children during the same time period.