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Volume 92.3

Noisy Factors in Law

Adriana Z. Robertson
Donald N. Pritzker Professor of Business Law, The University of Chicago Law School.

We thank Lucian Bebchuk, Alon Brav, Ryan Bubb, Ed Cheng, Quinn Curtis, Elisabeth de Fontenay, Jared Ellias, Jill Fisch, Joe Grundfest, Cam Harvey, Scott Hirst, Colleen Honigsberg, Marcel Kahan, Louis Kaplow, Jonathan Klick, Brian Leiter, Saul Levmore, Dorothy Lund, John Morley, Mariana Pargendler, Elizabeth Pollman, Roberta Romano, Paolo Saguato, Holger Spamann, George Vojta, and Michael Weber for valuable suggestions and discussions. This Article has benefited from comments by workshop participants at Columbia Law School, George Mason University Antonin Scalia Law School, Georgetown University Law Center, Harvard Law School, Stanford Law School, UC Berkeley School of Law, the University of Chicago Law School, the University of Oxford Faculty of Law, the University of Pennsylvania Carey Law School, the University of Toronto Faculty of Law, the University of Virginia School of Law, and the Washington University School of Law, as well as at the American Law and Economics Association Annual Meeting, the Corporate & Securities Litigation Workshop, the Labex ReFi-NYU-SAFE/LawFin Law & Banking/Finance Conference, and the Utah Winter Deals Conference. Robertson gratefully acknowledges the support of the Douglas Clark and Ruth Ann McNeese Faculty Research Fund. Katy Beeson and Levi Haas provided exceptional research assistance. All errors are our own.

Pat Akey
Associate Professor of Finance, University of Toronto; Visiting Professor, INSEAD.

We thank Lucian Bebchuk, Alon Brav, Ryan Bubb, Ed Cheng, Quinn Curtis, Elisabeth de Fontenay, Jared Ellias, Jill Fisch, Joe Grundfest, Cam Harvey, Scott Hirst, Colleen Honigsberg, Marcel Kahan, Louis Kaplow, Jonathan Klick, Brian Leiter, Saul Levmore, Dorothy Lund, John Morley, Mariana Pargendler, Elizabeth Pollman, Roberta Romano, Paolo Saguato, Holger Spamann, George Vojta, and Michael Weber for valuable suggestions and discussions. This Article has benefited from comments by workshop participants at Columbia Law School, George Mason University Antonin Scalia Law School, Georgetown University Law Center, Harvard Law School, Stanford Law School, UC Berkeley School of Law, the University of Chicago Law School, the University of Oxford Faculty of Law, the University of Pennsylvania Carey Law School, the University of Toronto Faculty of Law, the University of Virginia School of Law, and the Washington University School of Law, as well as at the American Law and Economics Association Annual Meeting, the Corporate & Securities Litigation Workshop, the Labex ReFi-NYU-SAFE/LawFin Law & Banking/Finance Conference, and the Utah Winter Deals Conference. Robertson gratefully acknowledges the support of the Douglas Clark and Ruth Ann McNeese Faculty Research Fund. Katy Beeson and Levi Haas provided exceptional research assistance. All errors are our own.

Mikhail Simutin
Professor of Finance, University of Toronto.

We thank Lucian Bebchuk, Alon Brav, Ryan Bubb, Ed Cheng, Quinn Curtis, Elisabeth de Fontenay, Jared Ellias, Jill Fisch, Joe Grundfest, Cam Harvey, Scott Hirst, Colleen Honigsberg, Marcel Kahan, Louis Kaplow, Jonathan Klick, Brian Leiter, Saul Levmore, Dorothy Lund, John Morley, Mariana Pargendler, Elizabeth Pollman, Roberta Romano, Paolo Saguato, Holger Spamann, George Vojta, and Michael Weber for valuable suggestions and discussions. This Article has benefited from comments by workshop participants at Columbia Law School, George Mason University Antonin Scalia Law School, Georgetown University Law Center, Harvard Law School, Stanford Law School, UC Berkeley School of Law, the University of Chicago Law School, the University of Oxford Faculty of Law, the University of Pennsylvania Carey Law School, the University of Toronto Faculty of Law, the University of Virginia School of Law, and the Washington University School of Law, as well as at the American Law and Economics Association Annual Meeting, the Corporate & Securities Litigation Workshop, the Labex ReFi-NYU-SAFE/LawFin Law & Banking/Finance Conference, and the Utah Winter Deals Conference. Robertson gratefully acknowledges the support of the Douglas Clark and Ruth Ann McNeese Faculty Research Fund. Katy Beeson and Levi Haas provided exceptional research assistance. All errors are our own.

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For years, academic experts have championed the widespread adoption of the “Fama-French” factors in legal settings. Factor models are commonly used to perform valuations, performance evaluations, and event studies across a wide variety of contexts, many of which rely on data provided by Professor Kenneth French. Yet these data are beset by a problem that the experts themselves did not understand: In a companion article, we documented widespread retroactive changes to French’s factor data. These changes are the result of discretionary changes to the construction of the factors, and they materially affect a broad range of estimates.

In this Article, we show how these retroactive changes can have enormous impacts in precisely the settings in which experts have pressed for their use. We provide examples of valuations, performance analyses, and event studies in which the retroactive changes have a large—and even dispositive—effect on an expert’s conclusions. Our analysis has several implications. First, it demonstrates that these data are not sufficiently reliable to be used by experts. Second, it demonstrates a phenomenon we call the law of conservation of judgment: Methodologies that appear objective still rely on judgment of one kind or another. Rather than eliminating judgment, they simply move it around. Finally, our analysis points to the problems that arise from the commingling of academic and commercial interests.

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