Why Did Dewey Beat Truman in the Pre-election Polls of 1948?

  • Frederick Mosteller


On election night in 1948, like many other people, I attended to the media later and later, and finally about 1:30 a.m. I abandoned hope of a decision and went to bed. Next morning we found that Harry Truman had defeated Thomas Dewey for the presidency of the United States, contrary to all the media wisdom. More important from a statistical point of view, the media had been continuously and confidently informed by the various polling organizations (such as Crossley, Gallup, and Roper) that Dewey would be the winner. These events led to my participation in a large social science study of pre-election polling.


Presidential Election Opinion Polling Polling Agency Polling Organization Russell Sage Foundation 
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  1. Baiman, R., Dodge, D., and Doop, K. (2005). The 2004 Presidential Election: Exit Poll Error or Vote Miscount? U.S. Count Votes' National Election Data Archive Project. itpolls/USCV_exit_poll_analysis.pdf.
  2. Crespi, I. (1988). Pre-election Polling: Sources of Accuracy and Error. New York: Russell Sage Foundation.Google Scholar
  3. Edison Media Research/Mitofsky International (2005). Evaluation of Edison/Mitofsky Election System 2004. http://www.electionmathematics. org/em-exitpolls/EvaluationJan192005.pdf.
  4. Fienberg, S. E. (2007). Memories of election night predictions past: Psephologists and statisticians at work. Chance, 20(4):8–17.MathSciNetGoogle Scholar
  5. Link, R. F. (1972). Election night on television. In J. M. Tanur, F. Mosteller, W. H. Kruskal, R. F. Link, R. S. Pieters, and G. R. Rising, editors, Statistics: A Guide to the Unknown. San Francisco: Holden-Day. 137–145. (Also appears in the 2nd edition [1979] and the 3rd edition [1989].)Google Scholar
  6. Mosteller, F., Hyman, H., McCarthy, P. J., Marks, E. S., and Truman, D. B., with the collaboration of L. W. Doob, D. MacRae, Jr., F. F. Stephan, S. A. Stouffer, and S. S. Wilks (1949). The Pre-election Polls of 1948. New York: Social Science Research Council Bulletin 60.Google Scholar
  7. Traugott, M., Highton, B., and Brady, H. (2005). A Review of Recent Controversies Concerning the 2004 Presidential Election Exit Polls. National Research Commission on Elections and Voting, Social Science Research Council.

Copyright information

© Springer Science+Business Media, LLC 2010

Authors and Affiliations

  • Frederick Mosteller
    • 1
  1. 1.BelmontUSA

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