## 8.03.2011

### The causal effect of going to my high school

An old high school friend* (crony?) sent me a Gothamist article linking to a new NBER paper by Abdulkadiroglu, Angrist, and Pathak on the causal effect of going to a New York City or Boston specialized public high school:
[...] We estimate the causal effect of exam school attendance using a regression-discontinuity design, reporting both parametric and non-parametric estimates. We also develop a procedure that addresses the potential for confounding in regression-discontinuity designs with multiple, closely-spaced admissions cutoffs. The outcomes studied here include scores on state standardized achievement tests, PSAT and SAT participation and scores, and AP scores. Our estimates show little effect of exam school offers on most students' achievement in most grades. We use two-stage least squares to convert reduced form estimates of the effects of exam school offers into estimates of peer and tracking effects, arguing that these appear to be unimportant in this context. On the other hand, a Boston exam school education seems to have a modest effect on high school English scores for minority applicants. A small group of 9th grade applicants also appears to do better on SAT Reasoning. These localized gains notwithstanding, the intense competition for exam school seats does not appear to be justified by improved learning for a broad set of students.
For the non-economists on this blog, Josh Angrist is one of the top empirical economists in the world (as well as enormously fun to read, viz my beach reading from last spring break) so having him evaluate your high school's academic outcomes is sort of like having John Madden come in and critique your JV football team.

As the authors openly admit in the paper, the experimental design (regression discontinuity, which was begging to be used to evaluate NYC specialized high school outcomes) is inherently limited in what it can say about students who were not near the cutoff. By assumption one treats students who barely make it into the school as being more or less the same as students who barely fail to make it in, and thus "going to the specialized high school" can be considered quasi-randomly assigned. Given that (and all of the tests that are run to make sure this assumption is valid) it looks like the simple act of going to a specialized high school when you're on the cusp is pretty nil. This may be surprising (and of course gets summarized in the Gothamist as "Stuyvesant, Bronx Science, Top Public Schools Not Worth It") but I think becomes less so with a little unpacking...

First, it's important to note that there's a very big difference between being in the bottom 10% at one school versus the top 10% at another. Kids who barely make it into a specialized high school are competing and comparing themselves against the remaining 90% of students who had little difficulty getting in. Meanwhile, their comparables at other schools are at the high end of the distribution. Given the complex nature of peer effects, teacher attention, and everything else, I'd say that these populations end up having very different experiences.

Second, I'd argue that a major reason specialized schools exist is not to help marginal kids do better but to allow superstar kids to do extraordinarily well. Stuy is famously referred to as a "haven for nerds" and like many top schools succeeds by virtue of giving driven and talented kids the opportunity and resources to do what they want. I imagine it'd be difficult to tease out (perhaps something geographic? I know a lot of kids from my neighborhood in the Bronx who went to Bronx Science despite getting into Stuy because it was much closer...) but I strongly suspect that the causal effect of going to the school is hugely nonlinear in ability.

Lastly, I'd say that even if we were to grant that the local treatment effect identified in the RD design reasonably proxied for the school's impact, test scores might not be the best place to look at outcomes. The specialized high schools are often touted as a means of leveling the playing field between poor (often immigrant) public school kids and rich private school ones. I suspect that if the outcomes of interest were not test scores but rather admission to elite colleges or wages in one's mid-20s, the results would be rather different.

In sum, the paper is super tightly identified, but given the populations they can plausibly claim to compare and the outcomes evaluated I'm not hugely surprised that the authors find little effect. My friends on Facebook and G+ who've been forwarding this to me can calm down. Unless they scored within 10% or so of the cutoff, in which case: sorry, guys, it was all for nothing...

* Full disclosure: I went to one of these schools (Stuyvesant) and *barely* made the cutoff, an experience that scared me into overperforming on standardized tests for the rest of my life.

1. Compare that result with results from this paper in AEJ Applied from this month:

Are High-Quality Schools Enough to Increase Achievement Among the Poor? Evidence from the Harlem Children’s Zone (working paper here)

Will Dobbie and Roland G. Fryer, Jr

Abstract: Harlem Children’s Zone (HCZ), an ambitious social experiment, combines community programs with charter schools. We provide the first empirical test of the causal impact of HCZ charters on educational outcomes. Both lottery and instrumental variable identification strategies suggest that the effects of attending an HCZ middle school are enough to close the black-white achievement gap in mathematics.  The effects in elementary school are large enough to close the racial achievement gap in both mathematics and ELA. We conclude with evidence that suggests high-quality schools are enough to significantly increase academic achievement among the poor. Community programs appear neither necessary nor sufficient.

I don't want any hate emails, but objective evaluation of NYC's public finance problem might suggest the reallocation of funds away from the highest end schools.  But of course, alternatively, there are all sorts of general equilibrium effects (eg. the economic value of Jesse going on from Stuyvesant to save the world) that are not captured in the Angrist paper.

2. One other thing I would also add that it's not that surprising that when you look at test scores among a population that's selected for being relatively good at taking tests (not even going into a discussion of what socioeconomic/cultural factors make someone good at test taking), the ability to take tests (whether it be the SAT or the entrance exam) isn't going to change much from a school based intervention. I would bet that test scores on the entrance exam are pretty highly correlated with SAT scores, since the skills being tested are the same.

3. This is outstanding post Thanks