A recent Huffington Post article calls Michigan’s public charter school sector “questionable” and spins the results of the most comprehensive study of these schools into something negative. Authors Joy Resmovits and Ashley Woods take issue with the references former Florida Gov. Jeb Bush made to a 2013 Stanford University report, claiming “the study of Michigan’s [charter] schools…is less definitive than [Gov. Bush] made it sound.”

The Stanford study says that the typical charter school student in Michigan made two months’ worth of learning gains annually in both reading and math compared to his or her peers in conventional schools. This finding was based on tracking individual charter school students’ test score growth over a five-year period and comparing these gains to those made by conventional school students who were similar in income, race, gender, English proficiency, special education needs, grade level and prior standardized test scores.

Resmovits and Woods acknowledge this finding, but then point out that the study also mentions that 80 percent of charters had average standardized reading test scores below the state average and the same was true for 84 percent of charters in math. The authors use this statistic — also referenced in a previous article by Resmovits — to characterize the Stanford study’s results on charter school performance in Michigan as a mixed bag.

This is either due to a poor understanding of the study, or an attempt to mislead readers. Indeed, CREDO Director Margaret Raymond said in the press release accompanying the study that it shows “…Michigan has set policies and practices for charter schools and their authorizers to produce consistent high quality across the state. The findings are especially welcome for students in communities that face significant education challenges.”

A snapshot comparison of charter schools’ average standardized test scores to the state average should not be weighted equally with an analysis that controls for a whole host of variables and tracks annual growth of individual students over many years. This simplistic comparison ignores the large impact socioeconomic factors have on a school’s average standardized test scores, which decades of research have borne out.

This statistic is also not very meaningful. Given the clear relationship between socioeconomic factors and student achievement, one should expect charters to have lower average standardized test scores. The Stanford study says that charter schools serve a larger portion of low-income students compared to the average for conventional schools — 70 percent to 43 percent, respectively.

Further, since no student is forced to attend a charter school, these schools’ existence depends on parents actively choosing to enroll their children. Charters, therefore, tend to locate in areas where parents are least satisfied with their state-assigned public schools. Not surprisingly, public schools with low standardized test scores tend to be the ones with which parents are the least satisfied, and students from these schools are the ones that are most likely to enroll in charter schools.

This poor interpretation of the Stanford study means that Resmovits and Woods are essentially criticizing charter schools for serving Michigan’s neediest students. All charters have room for improvement, to be sure, but the challenges they face serving a disproportionately large low-income student population should be taken into consideration when evaluating their performance, not ignored altogether. Based on the most rigorous and careful analysis ever done in Michigan, the results are clear: Charter schools are having a net positive impact on thousands of students in the Great Lake State

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