A secret of school performance...(admissions)

From kindergartens to colleges, one thing that helps a school produce lots of good graduates is if they admit lots of good students. Charter schools, which are publicly funded but privately operated, are supposed to admit students by lottery, and many run very public lotteries to make it clear that they aren't trying to influence the results. But it's tempting to cheat, hence this story from the NY Times:

Bronx Charter School Disciplined Over Admissions Methods

"A South Bronx charter school has been put on probation for what city education officials called “serious violations” of state law mandating random admissions, including possibly testing or interviewing applicants before their enrollment.



"The school, Academic Leadership Charter School, opened in 2009 and is the first New York City charter to be disciplined for violating the rules for random admissions.


"The violations go to the crux of the debate over charters, which are publicly financed but independently operated. Random admissions is a key tenet in most states, but critics have long contended that the schools surreptitiously weed out students who are unlikely to do well on standardized tests or are more difficult to educate.
...
"At most city charter schools, students are selected at public meetings where applicants’ names are picked from a box. But city officials found that at Academic Leadership, which has about 200 children in kindergarten through second grade, hundreds of applicants were left out of this year’s drawing. The lottery was supervised not by an impartial observer, but by a member of the parent association, the letter said. And while students who applied after the lottery should have been added to the waiting list, scores of them were not, it said.
“They are treating it like it’s a private school on the Upper East Side,” said a former school employee, who spoke on the condition of anonymity for fear of reprisal. “Like people are applying to Dalton. This isn’t Dalton.”
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At the other end of the spectrum from charter schools are exam schools, which are charged with admitting the best and the brightest. And maybe it's good for good students to be together with other good students (and not just good for a school's performance). I'm inclined to think that it is, but it's hard to show. A recent NBER paper suggests that good schools don't change the standardized exam scores for their students very much; the ones who just made the cutoff in public exam schools, and the ones who just missed getting in, do around the same on  tests.


The Elite Illusion: Achievement Effects at Boston and New York Exam Schools
by

Atila Abdulkadiroglu, Joshua D. Angrist, Parag A. Pathak
NBER Working Paper No. 17264
Issued in July 2011


Abstract: 
"Talented students compete fiercely for seats at Boston and New York exam schools. These schools are characterized by high levels of peer achievement and a demanding curriculum tailored to each district's highest achievers. While exam school students clearly do very well in school, the question of whether an exam school education adds value relative to a regular public education remains open. 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."