One More Time, NYC Charters Don’t Outperform Publics

Gary Rubinstein, an education blogger and math teacher at New York City’s Stuyvesant high school, has just posted a terrific analysis of Big Apple charter-school and public-school performance, showing once again that charters do not outperform publics–with one exception, which I’ll get to later. His analysis is based on test scores for the 2015 3-8 common core tests in math and ELA, which the city released in August. The Daily News reported that in the public schools, 34.2% of students met the math standards while 30.4% met the ELA standards, which was up by 1% and 2% respectively from the 2014 tests.

Rubinstein writes:

On the 2015 state tests, charter schools outperformed public schools in math with 44.2% meeting the standards while also doing worse than the public schools in reading with 29.3% meeting the standards.

To put these numbers into context, I crunched the numbers and summarized the results in a graph.  For each school I took the average of their math and ELA scores.  Then I took the most recent numbers for the school’s ‘Economic Need Index’ which includes the free lunch percent along with some other factors.

With graphs relating percent of free lunch to test score proficiency, there is always a strong negative correlation, as most people know.  The thing I wanted to see was if the charter schools had a higher percentage of ‘outliers’ than public schools.  In a sense, this is a bit like the coveted ‘value added’ measure that reformers like so much.  A school that is above the trend line would be a school with a greater than average value added.

Rubinstein finds that the vast majority of charter schools are not outperforming the public schools; about half of of the charters are above the trend line and half below.  Importantly, according to his calculations, most of the charters have an economic need index between .7 and .9 while there are a significant number of public schools that have an economic need index above .9.

The one exception is Success Academy, prompting Rubinstein to quip: “I can’t understand why charter supporters who are so focused on test scores are not out there insisting that all charter school resources be sent to expand Success Academy and the ‘yesterday’s news’ charters like KIPP, Democracy Prep, Harlem Children’s Zone, The Equity Project, etc. get shut down for poor performance.”

In this post, I showed how Success Academy schools cherry picks students who are less needy economically and have far fewer special needs students and English Language Learners than nearby public schools.

But, I also noticed that in Rubinstein’s graph, at least five public schools with comparable economic-need statistics performed as well, if not better, than the Success Academy schools. Several more performed nearly as well, with much higher levels of economic need.

A recent post by charter advocate Richard Whitmire is stunningly in sync with Rubinstein’s analysis. Whitmire concedes that of 6,440 charter schools, only 1,200 hundred are living up to their promise of outperforming public schools–i.e. less than 20 percent. Whitmire’s suggestion is to close 1,000 charter schools immediately. I guess its easy to experiment with other people’s children…

Given the decidedly unmiraculous performance of charter schools overall, and the high performance of many outlier public schools, wouldn’t it be more prudent to focus on learning from the outliers–both publics and a small number of experimental charters–how to improve public schools, rather than jettisoning the public system for a decidedly iffy alternative?

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2 Responses to One More Time, NYC Charters Don’t Outperform Publics

  1. Pingback: Links 10/14/15 | Mike the Mad Biologist

  2. keith swartz says:


    And yet, many parents want to leave the large public school districts, and also many parents (not necessarily the same cohort) want to enroll their children in charter schools. I am wryly amused by the primary demand of the UTLA to stop charters through legislation, as parents in their district are both leaving for charter schools and also just plain leaving the district. From 740,000 students ten years or so ago, LAUSD only “educates” around 510,000, with over 100,000 enrolled in charter schools and an additional 100,000+ having left the district. Spending in real terms is up something like 70+%, but most of the additional funds are going to finance the unsustainable pension system foisted on the State by UTLA and the rest of your team. To add to the injury, in the last five years or so, some 10,000 new employees have been added to LAUSD, none of them teachers.

    Your team is not only well funded through union dues, but are entrenched in the political system in such a way it will be fifty or more years before things change significantly. But time and change have a way of rendering power groups irrelevant, as free people seek remarkably clever and innovative ways of circumventing the system.

    Best, Keith

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