Charter school critics often point to high suspension and expulsion rates as the reasons charters tend to outperform their traditional public school counterparts. Anti-reform advocates have claimed that charters get rid of challenging students (English language learners, Special Ed, etc.) during testing by suspending or expelling them, which in turn artificially raises test scores.

A recent study conducted by the Center for Education Reform turns that theory on its head.

Using data from Washington, DC schools, the study found charter schools outperformed traditional public schools thoroughly. In fact, even if the suspension theory were true, scores were still higher. The study also examined suspension policy. It turns out Washington, DC’s disciplinary policy only permits suspension and expulsion for really serious violations, such as bringing a gun school, drug use or assaulting a member of staff. Charter schools have their own school boards which determine policy and are allowed to suspend students for less extreme reasons.

Here is a break-down of the study’s findings:

Instead of comparing raw numbers of disciplined students (which ultimately says nothing about student learning), this technique uses disciplinary data to artificially lower the number of proficient students at a charter school. The analysis estimates charter school performance very conservatively, and allows us to make a meaningful comparison between TPS and charters in what is effectively the “worst case scenario” for charter schools. … Charter schools retained their advantage over public schools in every year and subject where charter school performance was initially greater than TPS performance. Even after artificially lowering the proficiency rate to account for disciplined students, DC charter schools are still 2.47 percentile points more proficient in math and 2.65 points more proficient in reading on average. Furthermore, the actual change in proficiency rates as a result of making stringent disciplinary assumptions was small in absolute terms: at most, the charter school proficiency rate changed by about 2.4 percentile points. While some individual schools expelled many students (for example, one school expelled 68 students in a single year), 37% of charter schools went an entire school year without expelling any students. [Are Expulsion Rates Really Driving Charter School Success, Edspresso, 9/9/2013]

As you can see from the graphs above, even in the “worst case scenario,” charter schools still outperformed traditional public schools in DC.

Although it is possible that certain charters may have questionable disciplinary practices, it is not reasonable to suggest that all charters have this same issue, since disciplinary practices vary. More importantly, the study shows there isn’t any evidence to suggest that DC charter schools expel students in order to improve test scores.

It would be interesting to see how this study relates to local charter schools— Particular the ones that have been accused of high suspension rates.