Charter v. Public School Students: NAEP 2013 Performance

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On November 19, Diane Ravitch blogged in response to the Thomas B. Fordham Institute’s latest report on Ohio charter schools students’ National Assessment of Educational Progress (NAEP) performance – that students in traditional public schools significantly outperformed charter schools on the NAEP (the nation’s best test). In her post, Dr. Ravitch states, “It was findings like these that convinced me that the proliferation of charter schools was no panacea; that most charter schools were no better and possibly weaker than traditional public schools.” She asked us at VAMboozled! to probe further.

Thanks to Nicole Blalock, PhD and postdoctoral scholar at Arizona State University for this analysis and entry. Nicole writes:

Aside from discussions around the validity of utilizing NAEP “proficiency” as a reliable measure of academic learning, it is important to focus on a broader view of the performance of students in charter schools beyond a single state as analyzed in the aforementioned report. However, “it is difficult – not to mention scientifically invalid – to make blanket comparisons of charter schools to traditional public schools” (“Charter Schools”, n.d.). Nonetheless, because the proliferation of charters is reliant on theories that charters and increased school choice improve student achievement (Bulkley, 2003), it is also appropriate to do just this to evaluate charter effectiveness on a large-scale.

About half of states (n≈23) across the U.S. had enough charter schools to sample for the NAEP in 2013, in this case so that charter students’ performance could be compared to public school students’ performance. And in 2013, students in charter schools performed no differently than students in public schools in approximately half of these states (7-13 of the 23 states in each grade/subject pair). In about half of the states with significant performance differences (4-7 of the 7-13 states in each grade/subject pair) students attending public schools outperformed students attending charter schools, while in the other half charter school students outperformed public school students. The differences between charter and public schools students, by state, were really no different than the flip of a coin.

In four of the 7-13 states with a statistical difference between charter school students’ NAEP scores and public school students’ NAEP scores, statistical differences were observed for all grade/subject pairs tested. This occurred in the states of Alaska, Maryland, Ohio, and Pennsylvania. On average, in Alaska, students attending charter schools outperformed students in public schools by approximately 10 points in most grade/subject area tests and by more than 20 points in reading in grade 4. However, the National Alliance for Public Charters that ranked the 42 states with charter schools and the District of Colombia as per their charter school laws, ranked Alaska nearly the lowest (i.e., 41st of 43) for the “best” charter laws (“Measuring up to the model”, 2013). Put differently, the state whose charter school students performed among the best as compared to their public school peers just happened to be one of the worst charter states as externally ranked.

Otherwise, public school students outperformed charter school students in the other three states (i.e., Maryland, Ohio, and Pennsylvania) with consistent and significant score differences across the board. Maryland was one of two states to be ranked lower than Alaska for the “best” charter laws overall (i.e., 42nd of 43), and Ohio and Pennsylvania ranked in the middle of the pack (27th and 19th of 43 respectively). Each of these states demonstrated charter school student performance that lagged behind public school students by an average of 23 points.

In the other states with relatively larger numbers of charters, results were also mixed. Texas, a large state with over 200 charter schools, came in at the middle of the aforementioned “best” charter laws rankings (position 23rd of 43), and on average 4th grade charter school students in Texas scored 20 points lower on their NAEP reading assessment than their public school peers. That difference went away among grade 8 students tested in reading, and there was no average difference in performance measured among students tested in mathematics.

In California, another large charter state that boasts more than 1300 charter schools and ranked 7th of 43 in terms of “best” charter laws, its grade 4 charter students scored 10 points higher in reading than their public school peers, yet no differences in performance were measured for grade 8 students in reading or grade 4 and grade 8 students tested in mathematics.

In Arizona, a state often characterized by policy makers as the leader in school choice (Gresham, Hess, Maranto, & Milliman, 2000), a state with over 600 approved charters and a state ranking on the aforementioned list at 13th of 43 in terms of “best” charter laws, its charter and public school students performed about the same.

How did students in Minnesota, the state to write the first charter school law in 1991 and ranked 1st of the 43 for “best” charter laws fare? On average, there was no difference between the performance of students in charters and students in public schools there either.

Hence, it is clear that the performance of charter school students, when compared to public school students, were mixed in 2013 on the NAEP. Charter schools are certainly no panacea, as often claimed and/or intended to be.


Bulkley, K. (2003). A decade of charter schools: From theory to practice. Educational Policy 17(3), 317-342. doi:10.1177/0895904803017003002

Charter schools. (n.d.). Retrieved December 15, 2013, from

Gresham, A., Hess, F., Maranto, S., & Milliman, R. (2000). Desert bloom: Arizona’s free market in education. Phi Delta Kappan, 18(10), 751-757.

Measuring up to the model: A tool for comparing state charter school laws. (2013). Retrieved December 15, 2013, from

2 thoughts on “Charter v. Public School Students: NAEP 2013 Performance

  1. The validity of NAEP is precisely the point so you shouldn’t put the discussion aside. You need to know what you’re measuring. A competing hypothesis is that charters receive higher scores because they are teaching to the test. And there aren’t many differences between public and charter schools because public schools have been pressured into teaching to the test, too.

    Don’t accept the NAEP as a measure of “achievement”. It’s not.

  2. I think it might be important NOT to claim that this post does anything whatsoever to “evaluate charter effectiveness.” NAEP levels are not the same thing as school effectiveness. Period.

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