Star Ec Prof Caught in Academic Feud

Caroline Hoxby ’88 challenged over influential paper on school choice

Nearly five years after she published a landmark paper on school choice, Professor of Economics Caroline M. Hoxby ’88 is engaged in a fiery academic dispute over the paper’s integrity.

Princeton assistant professor Jesse M. Rothstein ’95 set off the public feud with Hoxby last spring, after he published a 69-page challenge to her 2000 paper asserting that he could not replicate Hoxby’s results. Rothstein additionally alleged that Hoxby—a well-known and influential figure in economics—delayed releasing data that would have allowed others to evaluate her conclusions.

In March, Hoxby responded by publishing a new defense of her scholarship. And in a recent interview, she speculated that the dispute was part of a larger issue of “race and gender bias” in higher education. Hoxby is black, while both Rothstein and his dissertation adviser at University of California, Berkeley, Professor David Card, are white.

In the contested 2000 paper, “Does Competition Among Public Schools Benefit Students and Taxpayers,” Hoxby argues that the ability to select among schools within a district positively influences the quality of schools.

Over the last two years, Rothstein has amassed a case that he believes invalidates the central findings of Hoxby’s paper. He set the economics field abuzz when he publicly challenged Hoxby’s data and findings in his March National Bureau of Economic Research (NBER) working paper. In addition to disputing Hoxby’s results, Rothstein implied that Hoxby’s initial refusal to share data from her paper with him violated American Economic Review (AER) policy.

AER editor Robert A. Moffitt, who declined to comment specifically on the Hoxby-Rothstein debate, said that AER’s policy about data availability had been in effect at the time, although not strictly enforced. In an e-mail, Moffitt wrote that Hoxby’s paper was published “prior to the strengthening of our data availability policy,” which occurred last March.

Hoxby published her response alongside Rothstein’s NBER working paper, dismissing his accusations.

To this day, the Hoxby-Rothstein quarrel—deemed unprecedented by some economists—continues to be a topic of water-cooler conversation in academic circles and on Internet blogs.

And the stage for the next round of dueling has already been set: Hoxby and Rothstein have each submitted their papers for publication in AER, a Supreme Court of sorts in the hierarchy of economics journals.

Both papers are still pending publication, but what began four months ago as a comment on a single paper has burgeoned into a full-fledged war of words, extending beyond the boundaries of Cambridge and Princeton and into the pages of the nation’s top economics journals.

DUELING PAPERS

School choice and the debate over school vouchers and charter schools have become contentious political issues in recent years.

Advocates for choice say it promotes healthy competition, forcing lower-performing schools to improve in order to attract students. Opponents say implementing a system of choice would worsen the public educational system, siphoning money from struggling schools into funds to pay for school vouchers.

Hoxby—who has consistently defended school choice—lent more fuel to supporters of a voucher system with the publication of her 2000 paper. The paper concludes, among other things, that students in areas with many competing school districts perform better on tests than students from areas with fewer school districts.

In making her case, Hoxby used the number of rivers and streams in a metropolitan area as a predictor of the number of districts in that area. She then employed a technique called instrumental variable regression to isolate the effect of school district size on test scores.

Employing this particular technique meant that Hoxby’s results depended crucially on her measurement of the streams. It is these measurements, and Rothstein’s own measurements of the streams, that are at the center of the academic dispute between the two economists.