Success Academy is the most famous and most controversial charter network in the country.  It is also the most mysterious.

They post excellent test scores on the state tests, we know that.  There are 40 schools serving about 10,000 students.  Though there is high teacher turnover, at a given time there are hundreds of Success Academy teachers.

But we hear so little first hand reports from the teachers, parents, or students at these schools.  I’ve seen horror stories in anonymous reviews on sites like this.  And I’ve spoken to parents of students who have transferred their children either voluntarily or involuntarily out of Success Academy schools.  The teachers at these schools keep a very low profile.  I suspect that they sign some kind of confidentiality agreement when they are hired.

Occasionally a negative story appears in the news about Success Academy.  Last year a student teacher took a video of a teacher ripping up a student’s math paper for giving an imperfect explanation of the math concept.  Then a story surfaced about how a principal had a got-to-go list of students he planned to force out.

Something that I think has not been reported widely enough is the attrition rate for Success Academy students.  Success Academy opened in 2006 with 83 Kindergarteners and 73 first graders.  Eleven years later there are now 17 twelfth graders set to be the first graduating class.  So we know for sure that at least 56 out of the initial 73 students, which is 77%, have left Success Academy before graduating.  But it is likely more than 77% attrition because Success Academy allows ‘backfilling’ in the early grades.  We don’t know how many of those 17 students currently in twelfth grade were among the 73 original first graders in 2006 and likely we will never know.  But even assuming that all 17 were among the original students, that is still 80% attrition.  Even over an 11 year period, that amounts to about 10% attrition per year for that cohort.

According to the Success Academy website, their annual attrition is just 10% which they say is better than the 13% attrition that is the city average.  The first thing that is misleading about these numbers is that since Success Academy does not ‘backfill’ beyond fourth grade which is a luxury that the public schools don’t have.  The other, more important, thing is that this 10% attrition number is not accurate.  Using the latest data from the New York City Department Of Education I have calculated the yearly attrition rate of the entire Success Academy network to be about 17%.

Here are the raw numbers:

The numbers in the first column, for example, mean that there were 1888 Kindergarteners in the network in 2015-2016 and 2006 First Graders in the network in 2016-2017 which meant that the cohort actually grew by 6%.

When you look at the overall numbers which count for attrition and also for backfilling in the early grades, the school seems to lose just 6% of its total population.  But this number out of context would be misleading since we don’t have any way of knowing how many students left and how many entered in the early grades.  Also notice that since their attrition in the early grades is hidden by their backfilling in those years and since the younger cohorts are so much larger than the older cohorts, that number is skewed.

By looking at just the grades where they don’t backfill which begins between the 4th grade and 5th grade years, for just the grades from 4th to 10th graders becoming 5th to 11th graders, we see attrition numbers that sometimes get into the 20s.  In total there were 2886 students from 4th to 10th grade in 2015-2016 and only 2409 students from 5th to 11th grade in 2016-2017 which is an attrition rate of 16.5%.  I think this is the most accurate measure of their attrition and I find it pretty amazing that each year this school can shed 1/6 of their students each year and that this fact is not widely reported.