Charter School Research

One often sees the claim that there is no evidence that charter schools are particularly effective. Some studies, to be sure, do show that charter schools look pretty similar to other public schools (see RAND 2009).

But there are many recent well-designed studies that give the advantage to charter schools.

1. Booker et al., RAND 2009 :

We find that charter high schools in Florida and in Chicago have substantial positive effects on both high school completion and college attendance. Controlling for observed student characteristics and test scores, univariate probit estimates indicate that among students who attended a charter middle school, those who went on to attend a charter high school were 7 to 15 percentage points more likely to earn a standard diploma than students who transitioned to a traditional public high school. Similarly, those attending a charter high school were 8 to 10 percentage points more likely to attend college. Using the proximity of charters and other types of high schools as exogenous instruments for charter high school attendance, we find even stronger effects in bivariate probit models of charter attendance and educational attainment. While large, our estimates are in line with previous studies of the impact of Catholic high schools on educational attainment.

2. Mathematica report for U.S. Department of Education (2010) (numerous jurisdictions):

We found that study charter schools serving more low income or low achieving students had statistically significant positive effects on math test scores, while charter schools serving more advantaged students—those with higher income and prior achievement—had significant negative effects on math test scores.

3. Mathematica study of KIPP middle schools nationwide (2010):

We find that students entering these 22 KIPP schools typically had prior achievement levels that were lower than average achievement in their local school districts. For the vast majority of KIPP schools studied, impacts on students’ state assessment scores in mathematics and reading are positive, statistically significant, and educationally substantial. Estimated impacts are frequently large enough to substantially reduce race/and income/based achievement gaps within three years of entering KIPP.

4. CREDO national study (2009), which, despite misleading reports, actually found that students improve more the longer they stay in charter schools.

As displayed in Figure 10, students generally experience a significant negative impact on learning in reading in their first year of charter enrollment, in the range of ‐.06 standard deviations. By the second year of charter school enrollment, students get a positive and significant impact on learning, but the magnitude is quite small at .01 standard deviations. Greater gains in reading are realized after three years; the average student with three years of charter schooling has a .02 standard deviation gain in learning. . . .

When looking at math learning gains the effects are more pronounced. Students in their first year of charter enrollment had gains that were ‐.09 standard deviations behind a typical TPS gain. The second year of enrollment produced no difference in the degree of learning gains. Mildly positive but significant impacts on learning gains are realized if a student remains in a charter school for three years or more, about .03 standard deviations in the third.

5. CREDO study of New York City (2010):

Overall the results found that the typical student in a New York City charter school learns more than their virtual counterparts in their feeder pool in reading and mathematics. In school-by-school comparisons New York City charters perform relatively better in math than in reading. In math, more than half the charter schools are showing academic growth that is statistically larger than their students would have achieved in their regular public schools. A third of charter schools show no difference, and 16 percent were found to have significantly lower learning. In reading, the numbers are not as strong, but show that nearly 30 percent outperform their local alternatives, 12 percent deliver worse results and about 60 percent are producing learning that is equivalent to their regular public school counterparts.

6. Hoxby, Murarky, and Kang (2009) (New York City):

On average, a student who attended a charter school for all of grades kindergarten through eight would close about 86 percent of the "Scarsdale-Harlem achievement gap" in math and 66 percent of the achievement gap in English. . . . 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.

7. Abdulkadiroglu et al. (2009) (Boston):

Among other key findings of the report: the impact of charter schools was particularly dramatic in middle school math.The effect of a single year spent in a charter school was equivalent to half of the black-white achievement gap. Performance in English Language Arts also significantly increased for charter middle school students, though less dramatically. Charter students also showed stronger performance scores in high school, in English Language Arts, math, writing topic development, and writing composition.

8. CREDO study of Indiana (2011):

Compared to the educational gains the charter students would have had in their traditional public schools, the analysis shows that students in Indiana charter schools make dramatically larger learning gains. While there are a small number of schools with inferior performance in reading, nearly half the charter schools have significantly more positive learning gains than their traditional public school counterparts. In math, none of the charter schools studied performs worse than the traditional public schools and nearly one quarter out-perform them.

9. Nisar (2010) (Milwaukee):

Charter schools with higher level of autonomy from the district in terms of financial budget, academic program, and hiring decisions, are effective. I show that students in these charter schools would read at a grade level higher than similar students who attend a traditional public school in three years. Irrespective of the type and the age of the charter school, race of the student, or grade level, attending a charter school has a positive effect on low achieving students. I show that these effects on low achieving students are substantial and are more than enough to eliminate the achievement gap in two years.

10. Hoxby and Rockoff (2004) (Chicago):

We find positive and statistically significant charter school effects for students who applied for Kindergarten through 3rd grade. For students applying to kindergarten or 1st grade, we find that charter school enrollment raised reading test scores by approximately 8 percentile points. For students applying to 2nd or 3rd grade, we find that enrollment raised math scores by approximately 10 percentile points and reading scores by approximately 4 percentile points.

Does this mean that all charter schools are good? Not by any means. CREDO's 2011 study of Pennsylvania, for example, found that students do less well in charter schools (primarily in virtual charters). And there are plenty of similar studies.

The point, rather, is that trying to prove "which one is better" on any kind of generalized basis is a fool's errand. Anyone who claims nationwide inferiority, parity, or superiority for charter schools is grossly oversimplifying what could be an interesting debate about why charter schools in some states or neighborhoods seem to be doing so much better while others are doing the same or worse. The education debate has to move beyond simplistic bromides for us to find out what sorts of state charter laws work, what sorts of charter school behavior are helpful, and the like.

For example, here's an August 2011 study from MIT analyzing what makes certain urban charter schools more successful than others: Angrist, Pathak, and Walters (2011):

Estimates using admissions lotteries suggest that urban charter schools boost student achievement, while charter schools in other settings do not. We explore student-level and school-level explanations for these differences using a large sample of Massachusetts charter schools. Our results show that urban charter schools boost achievement well beyond ambient non-charter levels (that is, the average achievement level for urban non-charter students), and beyond non-urban achievement in math. Student demographics explain some of these gains since urban charters are most effective for non-whites and low-baseline achievers. At the same time, non-urban charter schools are uniformly ineffective. Our estimates also reveal important school-level heterogeneity in the urban charter sample. A non-lottery analysis suggests that urban schools with binding, well-documented admissions lotteries generate larger score gains than under-subscribed urban charter schools with poor lottery records. We link the magnitude of charter impacts to distinctive pedagogical features of urban charters such as the length of the school day and school philosophy. The relative effectiveness of urban lottery-sample charters is accounted for by over-subscribed urban schools' embrace of the No Excuses approach to education.