As an underachiever from the Scarsdale Class of 1984, this new Stanford research by a professor named Minter-Hoxby caught my eye. Charter Schools appear to have a serious Treatment Effect. But, why do they? In thinking about the development of "human capability", the key unobservable is what goes on in the household. When parents see that their kid is in a better learning environment do they turn off the television and read more more and work more with their kids? Are home investments in the kid's human capital a substitute or complement of what goes in school? So, the "Kahn Conjecture" is that we need to take care that we have identified what actually is the "treatment". Parents will re-optimize once they see their child is making progress. I would like to see time diaries on what goes on at charter school households at night and at weekends and the counter-factual would parents have been reading to their kids and working less with them had they remained in public schools?


Looking back to Scarsdale, a big chunk of the "treatment" was the culture of excellence. I felt bad about not paying attention to my teachers and winging my homework. Now, I realize that I was front loading leisure . Only starting at age 22 when I went to Graduate School from October 1988 on have I have worked hard. From February 1966 until October 1988, I was in low gear and not too bugged about it.

Caroline is certainly correct that A lottery discontinuity does get you the right control group but the treatment group may be receiving multiple treatments including better parental inputs because they are in the treatment group. Should this second effect be counted as part of the treatment?


Suppose I am right about my parental "complements" story, does this chip away at Caroline's claims? I don't think so but it hints at necessary versus sufficient conditions for child excellence.

I would like to ask Caroline how Roland Fryer's "incentive experiments" and Heckman's work on dynamic complementarities (learning begets learning) fits into her claims. In the second case, should this predict heterogeneous treatment effects of participating in charter schools. Is she claiming that there is a uniform treatment effect here?



Prof. shows charter school efficacy

By: Marisa Landicho

Supporters of charter schools – schools that are privately managed but supported by public funds – have gained scientific credibility from a report released by Stanford economics Prof. Caroline Hoxby.

The report analyzed the New York State Exam results for over 41,000 charter and public school students, ranging from grades three through 12, in the New York City school system.

“On average,” the study concluded, “a student who attended a charter school for all of grades kindergarten to eight would close about 86 percent of the achievement gap in math and 66 percent of the ‘Scarsdale-Harlem’ achievement gap in English.”

Hoxby’s research, however, goes beyond just measuring test results of disadvantaged Harlem students against those of higher-performing, suburban Scarsdale students.

While previous studies have shown a similar increase in test scores, critics have argued that charter schools secure these higher scores by selecting only the students most likely to succeed. Professor Hoxby’s work has gained national attention for finding a method to overcome this objection, with mentions in the Washington Post and The New York Times.

Instead of comparing charter school students with the entire public school population, Hoxby only examined those students who had applied to the charter system and were either accepted (‘lotteried in’) or denied (‘lotteried out’) based on a lottery system.

“If the charter schools are doing better, then it can’t be because they are choosing better students,” she said. “That’s why we like to do these studies – it clarifies what we’re talking about and removes one of the potential problems.”

‘Lotteried in’ and ‘lotteried out’ students in the study are statistically equivalent in the categories of race, ethnicity, gender, prior test scores, percentage on free and reduced lunch and English Learner status.

“The parents go through the same application process, they are just as likely to send their kids to charter schools, and the only difference is a random lottery number,” Hoxby said.

With controls in place, the ‘lotteried in’ students ended up scoring higher than the ‘lotteried out’ group, testing an average of three points higher on Regents Exams for every year spent in the charter system.

Further study is needed to identify what aspects of charter schools contribute to better achievement, Hoxby said.

“I think that one of the big things to do is to follow these students when they get out of high school and go on to college,” she said. “We’d be disappointed if they did better in eighth grade then find they no longer improve.”

But Hoxby stressed that the results are not a mandate for charter schools.

“It’s about learning what makes schools work,” she said. “The point is to say, ‘O.K., look, here are a set of schools that are successful with disadvantaged students, what can we learn about these schools, and can we apply these lessons to public schools.’”

Tags: Caroline Hoxby, education

http://www.stanforddaily.com/cgi-bin/?p=1033147