Scholarly Comments on Academic Economics

Size Matters: The Standard Error of Regressions in the American Economic Review

by ,

*Steve Ziliak* is Associate Professor Economics in the School of Policy Studies at Roosevelt University. Professor Ziliak has previously taught at Emory University, Bowling Green State University, and the Georgia Institute of Technology. In 1996 he earned
*Deirdre McCloskey* is Distinguished Professor of Economics, History, English, and Communication, University of Illinois at Chicago; Professor of Social Thought, Academia Vitae, Deventer, The Netherlands; and Extraordinary Professor of Economics and of En

Abstract

Significance testing as used has no theoretical justification. Our article in the Journal of Economic Literature (1996) showed that of the 182 full-length papers published in the 1980s in the American Economic Review 70% did not distinguish economic from statistical significance. Since 1996 many colleagues have told us that practice has improved. We interpret their response as an empirical claim, a judgment about a fact. Our colleagues, unhappily, are mistaken: significance testing is getting worse. We find here that in the next decade, the 1990s, of the 137 papers using a test of statistical significance in the AER fully 82% mistook a merely statistically significant finding for an economically significant finding. A super majority (81%) believed that looking at the sign of a coefficient sufficed for science, ignoring size. The mistake is causing economic damage: losses of jobs and justice, and indeed of human lives (especially in, to mention another field enchanted with statistical significance as against substantive significance, medical science). The confusion between fit and importance is causing false hypotheses to be accepted and true hypotheses to be rejected. We propose a publication standard for the future: “Tell me the oomph of your coefficient; and do not confuse it with merely statistical significance.”

in Economics in Practice

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Volume (Issue)
1(2)
Pages
331-358
Published
JEL classification
A11, C12, C52
Keywords
statistical significance; economic significance; R.A. Fisher; role of economics
Article PDF Downloads
9,328 (updated 31 Dec 2011)

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