Tuesday, October 11, 2011

A Charter'd Libertine

School Choice, School Quality and Postsecondary Attainment, David Deming et al., NBER Working Paper, September 2011

Abstract: We study the impact of a public school choice lottery in Charlotte- Mecklenburg (CMS) on postsecondary attainment. We match CMS administrative records to the National Student Clearinghouse (NSC), a nationwide database of college enrollment. Among applicants with low-quality neighborhood schools, lottery winners are more likely than lottery losers to graduate from high school, attend a four-year college, and earn a bachelor's degree. They are twice as likely to earn a degree from an elite university. The results suggest that school choice can improve students' longer-term life chances when they gain access to schools that are better on observed dimensions of quality.


Measuring the Effect of Charter Schools on Public School Student Achievement in an Urban Environment: Evidence from New York City, Marcus Winters, Economics of Education Review, forthcoming

Abstract: This paper uses student level data from New York City to study the relationship between a public school losing enrollment to charter school competitors and the academic achievement of students who remain enrolled in it. Geographic measures most often used to study the effect of school choice policies on public school student achievement are not well suited for densely populated urban environments. I adopt a direct approach and measure charter school exposure as the percentage of a public school's students who exited for a charter school at the end of the previous year. Depending on model specification, I find evidence that students in schools losing more students to charter schools either are unaffected by the competitive pressures of the choice option or benefit mildly in both math and English.

I haven't read either of these papers. But I wonder if selection isn't driving both. In the first case, parents who care enough to get their kids to switch are the sort of parents who are more likely to encourage college. And in the second case, the parents of kids who are doing poorly in math and English are the ones who switch to charters, perhaps because (again) they want to ensure their kids succeed. That may well be wrong in one or both cases, of course. But selection is so tough in studies where you are measuring consequences of choices that are endogenous.

(Nod to Kevin Lewis)


The Spivonomist said...

I'd really like to see Manski Bounds get more popular. Selection bias is always difficult to address. We know this, yet we so frequently provide point estimates. How peculiar.

Dave Hansen said...

I don't see why endogeneity is a threat to the internal validity of the first paper. If the analysis was done correctly and the lottery is random w.r.t covariates that might affect later achievement, then the paper gives an accurate estimate of the causal effects of CMS's school choice program among kids whose parents care enough to get them in the charter school lottery. Even if this says nothing about the effects of school choice for all children (regardless of whether their parents would take advantage of school choice programs or not), the fact that school choice has such a big impact for parents that care is an important find.

Rhino said...

I'm thinking comparing lottery winners to losers accounts for selection. Aren't lottery losers still "parents who care enough to get their kids to switch are the sort of parents who are more likely to encourage college," but luck failed them?

MikeMcK said...

Rhino's got it. By entering the lottery, it shows parents "care"