More Charter Evidence

Diane Ravitch has declared that the Obama administration’s policy of expanding the number of charter schools has “no credible basis in research.”  This is just plain wrong.  And a new study coming out today from Stanford’s Caroline Hoxby demonstrates that she is even more wrong.

I’ve already noted that the highest quality studies — those that avoid bias from the self-selection of students into charter schools either with random-assignment or rigorous instrumental variable research designs — show significant academic benefits for students who attend charter schools instead of traditional public schools.  These studies examine the effect of charter schools in Massachusetts, Florida, Chicago, and New York City. 

And now add to that pile an updated study from Caroline Hoxby mentioned in today’s WSJ and NYT on New York City charter effects.  Students accepted by lottery into one of NYC’s charter schools in kindergarten and remained in a charter school through grade 8 closed the achievement gap with wealthy kids attending schools in Scarsdale entirely in math and two-thirds of the way in reading.

Critics are clinging to a study by Margaret Raymond at CREDO, which shows more mixed results.  While that study has the benefit of covering 15 states and DC, it can’t correct for the self-selection of students into charter schools like the highest quality studies linked above.  On average, students appear to be drawn to switching to charter schools because they are having trouble in their traditional public school.  Simply controlling for those students’ prior achievement and other observed demographic factors doesn’t quite correct for whatever negative factors may have caused students to switch to charters and that may continue to hinder their academic progress.  The CREDO study is as good as it can be given its approach, but I would have greater confidence in the consistent findings from several studies in different locations that do control for self-selection into charter schools.

8 Responses to More Charter Evidence

  1. Greg Forster says:

    If the study doesn’t correct for self-selection, how is it a “benefit” that it covers so many states?

  2. The CREDO study doesn’t fully correct for self-selection but it does a pretty good job of controlling for what it can. And breadth of coverage is important because we know that charter schools can be completely different things in different states.

    Frankly, it is plausible that charters are doing a great job in big cities, like NYC, Chicago, and Boston (from where most of our studies that do correct for self-selection come from), but do much less well in suburbs or rural areas. Big cities are the places where choice and competition is most limited in the absence of charters, so perhaps the introduction of charters makes a big difference. In suburbs you already have a fair amount of choice and competition. And in suburbs the traditional public schools may be powerful enough to block quality charters from entering their market. Since charters have to receive a license to operate from the traditional public schools or their allies, you may get sub-par charters in suburbs.

  3. Collin Hitt says:

    Hoxby released a memo alongside her new study, focusing exclusively on the CREDO study. From the conclusion: “The results of the CREDO study cannot be relied upon. This is most obviously because the study contains a serious statistical mistake that generates an automatic negative bias of considerable magnitude.” This bias severely underestimated the performance of charter schools relative to traditional public schools. Hoxby’s memo will be the definitive critique of the CREDO study, from now on.

  4. Collin Hitt says:

    Now I’m reading the Hoxby study itself. Look at this finding:

    “A student who attends a charter high school is about 7 percent more likely to earn a Regents diploma by age 20 for each year he spends in that school. For instance, a student who spent grades ten through twelve in charter high school would have about a 21 percent higher probability of getting a Regents diploma.”

    Holy Cow.

  5. jay greene says:

    This is great info, Collin. Thanks!

  6. Patrick says:

    So what exactly is Diane Ravitch’s position on reforming education if charters and real teacher evaluations “don’t” work?

  7. Greg Forster says:

    That’s a good question. If you find out the answer, make sure to let us all know. It’s hard to keep track given that her positions seem to be, well, fluid.

  8. Jay Greene says “On average, students appear to be drawn to switching to charter schools because they are having trouble in their traditional public school.”

    As we started our charter school experiment in Arizona (1993), the national research and local district data was startling: no correlation between parent’s rating of quality and academic productivity of schools. This suggested that school choice would not immediately improve academic achievement, but that it might have big impacts on juvenile crime. An alternative hypothesis was that the lack of school choice for over a hundred years had rendered parents completely unable to evaluate schools.

    After a decade and a half of significant school choice in Arizona, we now have a correlation between academic productivity and the percentage of parents rating their child’s school excellent.

    Arizona is number one in the nation in charter school choice. When you look at our juvenile crime stats since we started our charter program, our violent crime went down 25% more than the national violent juvenile crime rate went down. The proportion of our juveniles in detention, jail and prison went down by almost 40 percent.

    Our rural counties did not participate in this same trend. However, their penetration of charter schools is much lower than the penetration in our urban counties.

    All of this is highly relevant as the spectacular data from New York city charter schools begins to influence the debate over charter school choice. In New York City, the cost per student has just exploded from 2002 when Mayoral takeoever happened (budget $12.5 billion) to 2008 (budget $21 billion). This is the enormous price Klein had to pay the unions to bring charter schools to New York. The impact this taxation load had on New York City appears to have been devastating economically. More than 8% of New York City’s population left without offsetting domestic migration. The people who left had much much higher incomes than the international migrants who replaced them and the people who stayed.

    In Arizona, we reversed this policy set. Charter schools were not only costless to bring, they have saved us money each year. On a cost per student basis, our charter public schools save us about $180 million per year in reduced cost relative to district schools. This costless expansion has enabled us to quickly grow charter schools in Arizona.

    Can we match New York City’s academic gains from charter schools? This year, we had our most sophisticated study of the academic gains of all schools. In the study, students were matched based on a three year trajectory of academic results. In other words students in a school with a trajectory of 42nd percentile, 35th percentile, 47th percentile in the three prior years were all compared for academic gains in the current year.

    Of over 1300 schools compared, the top academic gain school in Arizona is a charter school unlike any I’ve ever seen before. It is a hybrid of distance learning using national dominant distance learning software mixed with classes on academic subjects. The architecture of the school is unique. It borrows from Finland’s concept that the observed classroom performs at a higher level than the unobserved classroom. The rear end of these classrooms are huge plate glass windows which put the teacher on stage without distracting the students. The center of the school is one large room with several hundred students persuing their own individual learning via software with 7 circulating coaches (teachers). Talk about massively differentiated instruction. The rearends of the classrooms point towards this one large room allowing the classroom teachers to be observed by the students and the circulating coaches.

    While I was watching touring the central classroom, I observed through the plate glass window an algebra class physically act out an algebraic equation. I’m an engineer by trade but I’ve never seen that before. As I watched it, I also realized that I would never forget it or the structure of the algebraic equation they were acting out either.

    By only allowing proven technology, NewYork City likely will not allow a Carpe Diem to start up for another decade. Carpe Diem is a completely new vision. In Arizona, we need only one replicatable high performance model that can perform at our cost levels. We appear to have many. Of the top one hundred academic gains (value added) schools, half were charter public schools. Ten percent of the marketplace is providing half the high peformers in Arizona.

    New York’s extravagance has proven the charter school point, but it has brought them to a dead end. A major point of education is to provide economic opportunity. If your schools are so expensive that the jobs are destroyed, the education is meaningless.

    As for Diane Ravitch, go easy on her. All of her books reveal her to be relatively friendly towards school choice. Her battle with Joel Klein has gotten so personal it warps her better judgement. Joel Klein is a control freak who has needlessly alienated her by making it excrutiatingly difficult for her to get simple information she needs to perform her studies. As the world’s expert on NewYork city schools (read her books), this couldn’t be more personal.

    John Huppenthal
    Chairman, Arizona Senate Education Committee

    However, it is relevant to the current debate in two ways. First, Joel Kline, Chancellor of New York, implicity criticizes Arizona in how he describes thei

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