According to the Huffington Post, last year The Detroit News attempted to compare student academic achievement between Detroit-area public charter school high schools and their conventional Detroit Public Schools counterparts.

The News found that just six of 25 Detroit public charter schools reported higher math or science proficiency rates than DPS high schools.

A new Mackinac Center study provides a more complete analysis of student academic achievement, and finds that Detroit public charter schools are doing better than their conventional public high school counterparts.

The problem with analyses like The News’, which considered school performance by student test scores alone, is that those scores do not take into account student academic advantages and disadvantages.

Studies have repeatedly found that socioeconomic status can have a substantial effect on student academic performance. A better way to measure how a school is doing is to take into account whether its students come from higher or lower income families. That way, the analysis can identify schools that, given their students’ socioeconomic status, are (and are not) exceeding expectations.

Our recent study did just this and produced a “Context and Performance Score,” based on four years of MME and ACT scores (for a complete description of methodology, see pages 3-5 of the study). Schools with “CAP Scores” above 100 are besting their predicted performance compared to the rest of the state, while scores below 100 indicate that a school is falling below predictions.

The average CAP Score for the 12 Detroit charter public high schools included in the study was 100.4 — not great, but slightly above the state standard. But the average for the 20 conventional DPS high schools was only 84.2.

Of the 10 highest scoring high schools in Detroit (excluding selective high schools), only three were conventional public high schools. Moreover, of the bottom 10 high schools, all but one was a conventional public high school.

There is a simple reason why Detroit public charter schools report lower test scores than conventional public high schools and yet still receive higher CAP Scores. On average, Detroit public charter schools enroll a larger share of students from low-income families.

The average Detroit public charter school reported that more than 80 percent of its students were from low-income households, whereas the average conventional public schools in the city had 68 percent of its student from similar backgrounds.

Charter schools may not be a panacea for all of public education’s woes, but they certainly appear to be outperforming the competition in Detroit.

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