IDEAS home Printed from
MyIDEAS: Log in (now much improved!) to save this paper

Overconfidence by Bayesian Rational Agents

  • Eric Van den Steen


    (Harvard Business School, Strategy Unit)

This paper derives two mechanisms through which Bayesian-rational individuals with differing priors will tend to be relatively overconfident about their estimates and predictions, in the sense of overestimating the precision of these estimates. The intuition behind one mechanism is slightly ironic: in trying to update optimally, Bayesian agents overweight information of which they over-estimate the precision and underweight in the opposite case. This causes overall an over-estimation of the precision of the final estimate, which tends to increase as agents get more data.

If you experience problems downloading a file, check if you have the proper application to view it first. In case of further problems read the IDEAS help page. Note that these files are not on the IDEAS site. Please be patient as the files may be large.

File URL:
Download Restriction: no

Paper provided by Harvard Business School in its series Harvard Business School Working Papers with number 11-049.

in new window

Length: 23 pages
Date of creation: Nov 2010
Date of revision:
Handle: RePEc:hbs:wpaper:11-049
Contact details of provider: Postal:
Soldiers Field, Boston, Massachusetts 02163

Phone: 617.495.6000
Web page:

More information through EDIRC

References listed on IDEAS
Please report citation or reference errors to , or , if you are the registered author of the cited work, log in to your RePEc Author Service profile, click on "citations" and make appropriate adjustments.:

as in new window
  1. Thomas S. Wallsten & David V. Budescu & Rami Zwick, 1993. "Comparing the Calibration and Coherence of Numerical and Verbal Probability Judgments," Management Science, INFORMS, vol. 39(2), pages 176-190, February.
  2. Kent Daniel & David Hirshleifer & Avanidhar Subrahmanyam, 1998. "Investor Psychology and Security Market Under- and Overreactions," Journal of Finance, American Finance Association, vol. 53(6), pages 1839-1885, December.
  3. Matthew Rabin & Joel L. Schrag, 1999. "First Impressions Matter: A Model of Confirmatory Bias," The Quarterly Journal of Economics, Oxford University Press, vol. 114(1), pages 37-82.
  4. Michael D. Grubb, 2006. "Selling to Overconfident Consumers," Discussion Papers 06-018, Stanford Institute for Economic Policy Research.
  5. Markus K. Brunnermeier & Jonathan A. Parker, 2002. "Optimal Expectations," Working Papers 146, Princeton University, Woodrow Wilson School of Public and International Affairs, Discussion Papers in Economics.
  6. J. Michael Harrison & David M. Kreps, 1978. "Speculative Investor Behavior in a Stock Market with Heterogeneous Expectations," The Quarterly Journal of Economics, Oxford University Press, vol. 92(2), pages 323-336.
  7. Arnoud W.A. Boot & Radhakrishnan Gopaian & Anjan V. Thakor, 2006. "Market Liquidity, Investor Participation and Managerial Autonomy: Why do Firms go Private?," Tinbergen Institute Discussion Papers 06-011/2, Tinbergen Institute.
  8. Morris, Stephen, 1995. "The Common Prior Assumption in Economic Theory," Economics and Philosophy, Cambridge University Press, vol. 11(02), pages 227-253, October.
  9. Shimon Kogan, 2009. "Distinguishing the Effect of Overconfidence from Rational Best-Response on Information Aggregation," Review of Financial Studies, Society for Financial Studies, vol. 22(5), pages 1889-1914, May.
  10. Robert Aumann & Adam Brandenburger, 2014. "Epistemic Conditions for Nash Equilibrium," World Scientific Book Chapters, in: The Language of Game Theory Putting Epistemics into the Mathematics of Games, chapter 5, pages 113-136 World Scientific Publishing Co. Pte. Ltd..
  11. Daron Acemoglu & Victor Chernozhukov & Muhamet Yildiz, 2006. "Learning and Disagreement in an Uncertain World," NBER Working Papers 12648, National Bureau of Economic Research, Inc.
  12. Eric Van den Steen, 2004. "Rational Overoptimism (and Other Biases)," American Economic Review, American Economic Association, vol. 94(4), pages 1141-1151, September.
  13. John Geanakoplos, 2009. "The Leverage Cycle," Cowles Foundation Discussion Papers 1715, Cowles Foundation for Research in Economics, Yale University.
  14. Jose A. Scheinkman & Wei Xiong, 2003. "Overconfidence and Speculative Bubbles," Journal of Political Economy, University of Chicago Press, vol. 111(6), pages 1183-1219, December.
  15. Morris, Stephen, 1994. "Trade with Heterogeneous Prior Beliefs and Asymmetric Information," Econometrica, Econometric Society, vol. 62(6), pages 1327-47, November.
  16. Robert J. Aumann, 1998. "Common Priors: A Reply to Gul," Econometrica, Econometric Society, vol. 66(4), pages 929-938, July.
  17. Hong, Harrison & Stein, Jeremy, 2007. "Disagreement and the Stock Market," Scholarly Articles 2894690, Harvard University Department of Economics.
  18. K. J. Arrow, 1964. "The Role of Securities in the Optimal Allocation of Risk-bearing," Review of Economic Studies, Oxford University Press, vol. 31(2), pages 91-96.
  19. Kent D. Daniel, 2001. "Overconfidence, Arbitrage, and Equilibrium Asset Pricing," Journal of Finance, American Finance Association, vol. 56(3), pages 921-965, 06.
  20. Faruk Gul, 1998. "A Comment on Aumann's Bayesian View," Econometrica, Econometric Society, vol. 66(4), pages 923-928, July.
Full references (including those not matched with items on IDEAS)

This item is not listed on Wikipedia, on a reading list or among the top items on IDEAS.

When requesting a correction, please mention this item's handle: RePEc:hbs:wpaper:11-049. See general information about how to correct material in RePEc.

For technical questions regarding this item, or to correct its authors, title, abstract, bibliographic or download information, contact: (Soebagio Notosoehardjo)

If you have authored this item and are not yet registered with RePEc, we encourage you to do it here. This allows to link your profile to this item. It also allows you to accept potential citations to this item that we are uncertain about.

If references are entirely missing, you can add them using this form.

If the full references list an item that is present in RePEc, but the system did not link to it, you can help with this form.

If you know of missing items citing this one, you can help us creating those links by adding the relevant references in the same way as above, for each refering item. If you are a registered author of this item, you may also want to check the "citations" tab in your profile, as there may be some citations waiting for confirmation.

Please note that corrections may take a couple of weeks to filter through the various RePEc services.

This information is provided to you by IDEAS at the Research Division of the Federal Reserve Bank of St. Louis using RePEc data.