P-Curve: A Key to the File Drawer

Journal of Experimental Psychology: General, Forthcoming

14 Pages Posted: 24 Apr 2013 Last revised: 8 Jul 2014

Uri Simonsohn

University of Pennsylvania - The Wharton School

Leif D. Nelson

University of California, Berkeley - Haas School of Business

Joseph P. Simmons

University of Pennsylvania - The Wharton School

Date Written: April 24, 2013

Abstract

Because scientists tend to report only studies (publication bias) or analyses (p-hacking) that “work”, readers must ask, “Are these effects true, or do they merely reflect selective reporting?” We introduce p-curve as a way to answer this question. P-curve is the distribution of statistically significant p-values for a set of studies (ps < .05). Because only true effects are expected to generate right-skewed p-curves – containing more low (.01s) than high (.04s) significant p-values – only right-skewed p-curves are diagnostic of evidential value. By telling us whether we can rule out selective reporting as the sole explanation for a set of findings, p-curve offers a solution to the age-old inferential problems caused by file-drawers of failed studies and analyses.

Keywords: p-hacking, publication bias, file drawer, science, statistics, judgment, decision making

Suggested Citation

Simonsohn, Uri and Nelson, Leif D. and Simmons, Joseph P., P-Curve: A Key to the File Drawer (April 24, 2013). Journal of Experimental Psychology: General, Forthcoming. Available at SSRN: https://ssrn.com/abstract=2256237

Uri Simonsohn (Contact Author)

University of Pennsylvania - The Wharton School ( email )

3730 Walnut Street
JMHH 500
Philadelphia, PA 19104-6365
United States

Leif D. Nelson

University of California, Berkeley - Haas School of Business ( email )

545 Student Services Building, #1900
2220 Piedmont Avenue
Berkeley, CA 94720
United States

Joseph P. Simmons

University of Pennsylvania - The Wharton School ( email )

3733 Spruce Street
Philadelphia, PA 19104-6374
United States

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