At a time when the question of how to best serve our neediest students at all schools is a key focus at the local and national levels, media analyses of the impact of student attrition at charters and district schools can be a useful contribution to the discussion. Unfortunately, an article recently published by SchoolBook misses the key point of this question in its failure to acknowledge that charter attrition’s effects come not from the number or type of students who leave, but from most charters’ decisions not to replace those students.
Gary Miron did a great job addressing this issue in his recent study on KIPP, and Mathematica recently confirmed some of his key findings (though they argued that the impact of these practices were relatively minimal).
In general, Miron and others have shown that both urban charters and urban district schools serve populations with high rates of student mobility — every year, relatively high percentages of students change schools in New York and other cities, and students who change schools (in general) tend to be lower achieving and have higher needs. This is what the SchoolBook article focuses on — if you just look at the percentage and type of students who leave schools in any given year, you’re not going to find big differences between district and charter schools.
The key difference is that in district schools, the students who transfer out are replaced by equally needy students who transfer in, including in higher grades. Overall, this keeps enrollment numbers and overall percentages of high-need students fairly stable — in a K-5 district school, if you have 50 kindergartners arrive in 2012, you’ll see roughly 50 5th graders graduate six years later. Not all those students will have started as kindergartners, but those who left will have been replaced by students with fairly similar demographics and achievement levels.
In contrast, even charter advocates admit that most charters choose not to replace students who leave with incoming transfer students, especially in upper grades. This means that at charters, the neediest students are the most likely to leave before graduation, but either they aren’t replaced or they’re replaced in very limited numbers. This is why you’ll often tend to see graduating classes at charters which are much smaller than entering classes.
Based on what we know about the demographics of students who transfer compared to those who stay in schools, the upper-grade students who remain in a charter with high attrition will tend to be those with relatively lower needs and higher academic achievement. In NYC, we’ve shown that the charter middle schools with the highest attrition and non-replacement rates are also the same ones which show the greatest increases in scores in their highest grades. The Mathematica study showed that at KIPP, incoming transfer students tended to come in with higher achievement levels than students who transferred into district schools, a pattern also noted by the principal of the charter school highlighted in the SchoolBook article when discussing his school’s test score increases.
The other element of this that the article doesn’t fully address is the impact of the different discipline codes at the charters. The quotes from the parents and charters leaders in the article are fairly contradictory on this point — they acknowledge that disagreements about discipline were a primary factor in making these students leave the school, but don’t define this as being “kicked out.” The lack of a good way to either measure (1) how frequently these “nudge out” transfers happen or (2) the impact the exit of students with discipline issues has on the remaining students’ academic performance are major problems with the research in this area. Some charters do have high rates of suspensions, but lower-level types of discipline are much harder to track.
Overall, the fact that this article doesn’t even acknowledge that practices around attrition and replacement represent a legitimate difference between charters and district schools makes its analysis significantly less useful and more misleading than those from the Charter School Center itself or the researchers at Mathematica — and very disappointing.