Charter Schools

The coalition agreement between ACT and National has provision for trial charter schools in South Auckland and Christchurch:

With respect to education, the parties have, in particular, agreed to implement a system, enabled under either sections 155 (Kura Kaupapa Maori) or 156 (Designated character schools), or another section if appropriate, of the Education Act, whereby school charters can be allocated in areas where educational underachievement is most entrenched. A series of charters would initially be allocated in areas such as South Auckland and Christchurch. Iwi, private and community (including Pacific Island) groups and existing educational providers would compete to operate a local school or start up a new one. Schools would be externally accountable and have a clearly-defined, ambitious mission. Public funding would continue to be on a per-child basis. (Details are included in the attached Annex)

So, what evidence do we have on the performance of charter schools in the States?

First, a note of caution in all the American studies - charter schools operate under regulatory constraints and vehement opposition from American teachers unions, both of which may affect observed results. Further, suppose a charter school opens in a neighbourhood and you find higher test scores among the students who go there compared to those who stay at the public school. Are the results due to differences in school quality, or selection effects? Two kinds of selection effects will be relevant - schools may try to get the best students, and high quality parents may be more likely to flip their kids out of failing schools. DimPost seems to think everything's due to selection; it would have been more helpful had he hit Google Scholar.

There are ways of controlling for selection effects. Here's Josh Angrist and coauthors from 2009, HT: Marginal Revolution. They used a lottery as random assortment mechanism: Boston charter schools were oversubscribed, so a lottery was used to determine which kids got in. So Angrist can compare those who won lotto with those who didn't. Remember, this is Josh-freaking-Angrist. The econometrics here aren't going to be wrong.

Charter schools are publicly funded but operate outside the regulatory framework and collective bargaining agreements characteristic of traditional public schools. In return for this freedom, charter schools are subject to heightened accountability. This paper estimates the impact of charter school attendance on student achievement using data from Boston, where charter schools enroll a growing share of students. We also evaluate an alternative to the charter model, Boston's pilot schools. These schools have some of the independence of charter schools, but operate within the school district, face little risk of closure, and are covered by many of same collective bargaining provisions as traditional public schools. Estimates using student assignment lotteries show large and significant test score gains for charter lottery winners in middle and high school. In contrast, lottery-based estimates for pilot schools are small and mostly insignificant. The large positive lottery-based estimates for charter schools are similar to estimates constructed using statistical controls in the same sample, but larger than those using statistical controls in a wider sample of schools. The latter are still substantial, however. The estimates for pilot schools are smaller and more variable than those for charters, with some significant negative effects.

Upshot: charter schools do better, and because they're outside of collective bargaining and because they face the risk of shutting down if parents don't choose to send their kids there.

Other evidence?

• In another randomized trial, Caroline Hoxby finds substantial gains for students winning entry to charter schools in New York. Here's an ungated version of the paper. Here's the report.
• New Orleans moved heavily towards charter schools after Katrina; outcomes improved.

Here's Caroline Hoxby explaining her work.

Caroline Hoxby: The Promise and Performance of Charter Schools from The Hoover Institution on FORA.tv

I'd not be surprised if charter schools weren't already in National's plans, but it's still a nice win for ACT.

And it's great fun to watch all those who rallied for MMP now whining about post-election coalition deals. You guys should have ticked the box for FPP.

When you go out to do your own literature search, be sure to upweight results from studies that control for selection effects either by this kind of randomized lottery treatment, or by instrumental variable approaches (like this one). Put less weight on studies that just compare charter and regular schools without addressing selection issues.