In my last post, I alluded to a major difference in charter school suspension rates vs traditional school suspension rates. This was wrong and shortsighted. If you look at averages, charter schools in Los Angeles Unified suspend at a rate that is 3 times higher than traditional schools. That is an unduplicated number, meaning that we are counting the total percent of students who were suspended at any point in the school year. But averages are deceiving.
The immediate question I had was whether this is a distributed number, or the result of a few charter schools that suspend at high rates. Or, is the high suspension rate evenly distributed? A good way to look at this is something we all learn in 6th grade math: The histogram.
For those of you who have lost touch with your sixth grade math self, a histogram presents counts of all the schools that fall into a “bucket”. So the large first column you see there are the 160 or so schools that have a suspension rate between 0% and 1%.
Looking at it this way, it is clear that a plurality of charter schools have very low suspension rates. In fact, the median charter school has a suspension rate of 0.2%. However, there are about 60 high-suspension rate charters that drag up the average. Those sixty charters account for 20% of the charter school population in Los Angeles, but also account for 66% of the unduplicated suspensions at charter schools. If those 60 charter schools weren’t included in the count, the remainder of the charter schools in Los Angeles would have the same suspension rate as the rest of the district.
This means that, contrary to what I said in the last post, the vast majority of charter schools do not really have higher suspension rates. Some do, but most do not.