"In addition, some KIPP schools show high attrition, especially for those students entering the schools with the lowest test scores. A 2008 study by SRI International found that although KIPP fifth-grade students who enter with below-average scores significantly outperform peers in public schools by the end of year one, "... 60 percent of students who entered fifth grade at four Bay Area KIPP schools in 2003-04 left before completing eighth grade." The report also discusses student mobility due to changing economic situations for student's families, but does not directly link this factor into student attrition. Six of California's nine KIPP schools, researched in 2007, showed similar attrition patterns. Figures for schools in other states are not always as readily available."Administrators have long known that the simplest and most reliable way to improve a school's performance is by selection and attrition of the student body. This works in the obvious, direct ways -- if you drop the kids who disrupt class and/or can't master the material, test scores and classroom management metrics will go up -- but there are at least a couple of indirect effects that are as, or more, powerful.
One is the eighty/twenty rule. Some students take more time than others and, not surprisingly, the students who lower a school's test average and management metrics are the ones who consume the most time and resources.
Even more significant are peer effects. K through 12 students are particularly sensitive to perceived social norms. By selectively removing certain students from the population, you can easily create a high degree of conformity to an almost ideal set of behaviors and attitudes.
Most educators look at getting rid of students as a last resort. The prevailing attitude is that you are there to help all the kids, not just the easy ones. You will find exceptions, of course, like principals who are a little too eager to expel certain students or find ways to influence which students are assigned to other schools, but they are forced to work around rules that discourage this behavior.
For charter schools, though, these selective factors are built into the system. Here's the deal that college prep charter schools offer, if the students go through an involved application/induction process, take more difficult courses during a longer school day and do more homework, they will have a better chance at academic and professional success. These schools have automatically limited their pool of applicants to kids who consider academic and professional success both desirable and attainable and who come from supportive, involved families that are willing to make a real effort to give their children a chance to succeed.
(quick clarification: we are talking about selection processes that favor certain attitudes and behaviors. We are NOT talking about favoring students with high test scores. Many reporters and, God help us, researchers have failed to grasp this distinction.)
Charter schools segregate out a group of students who tend to be, to put it bluntly, easy to teach. This is not an entirely bad thing. Though there are concerns about this being a zero-sum-game, there is something to be said for making sure that every neighborhood has at least one educational bright spot.
It is, however, an entirely bad thing when dishonest or naive observers evaluate these schools without taking these systemic advantages into account and it is worse still when unscrupulous administrators try to build on those systemic advantages by cooking the data through selective attrition.
If you start with a student body made up almost entirely of kids who want to be in school, avoid gangs and graduate from college, who are supported by families with the same goals, you should expect relatively low attrition. When you see the opposite, you should certainly be suspicious. Even the most inept administrator can look good if you allow him or her to pick the most promising students out of an already select group.