When Does Making Detailed Predictions Make Predictions Worse?

Kelly, T. F., & Simmons, J. P., When does making detailed predictions make predictions worse? Journal of Experimental Psychology: General, Forthcoming

15 Pages Posted: 26 May 2016 Last revised: 7 Sep 2016

Theresa F. Kelly

Washington University in Saint Louis - John M. Olin Business School; RAND Corporation

Joseph P. Simmons

University of Pennsylvania - The Wharton School

Date Written: September 6, 2016

Abstract

In this paper, we investigate whether making detailed predictions about an event worsens other predictions of the event. Across 19 experiments, 10,896 participants, and 407,045 predictions about 724 professional sports games, we find that people who made detailed predictions about sporting events (e.g., how many hits each baseball team would get) made worse predictions about more general outcomes (e.g., which team would win). We rule out that this effect is caused by inattention or fatigue, thinking too hard, or a differential reliance on holistic information about the teams. Instead, we find that thinking about game-relevant details before predicting winning teams causes people to give less weight to predictive information, presumably because predicting details makes useless or redundant information more accessible and thus more likely to be incorporated into forecasts. Furthermore, we show that this differential use of information can be used to predict what kinds of events will and will not be susceptible to the negative effect of making detailed predictions.

Keywords: Decision making, Forecasting accuracy, Accessibility, Prediction Specificity

Suggested Citation

Kelly, Theresa F. and Simmons, Joseph P., When Does Making Detailed Predictions Make Predictions Worse? (September 6, 2016). Kelly, T. F., & Simmons, J. P., When does making detailed predictions make predictions worse? Journal of Experimental Psychology: General, Forthcoming. Available at SSRN: https://ssrn.com/abstract=2784769 or http://dx.doi.org/10.2139/ssrn.2784769

Theresa F. Kelly (Contact Author)

Washington University in Saint Louis - John M. Olin Business School ( email )

One Brookings Drive
Campus Box 1133
St. Louis, MO 63130-4899
United States

RAND Corporation ( email )

1776 Main Street
P.O. Box 2138
Santa Monica, CA 90407-2138
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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