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The Sealed-Bid Abstraction in Online Auctions


  • Robert Zeithammer

    () (Anderson School of Management, University of California, Los Angeles, Los Angeles, California 90095)

  • Christopher Adams

    () (Federal Trade Commission, Washington, DC 20580)


This paper presents five empirical tests of the popular modeling abstraction that assumes bids from online auctions with proxy bidding can be analyzed "as if" they were bids from a second-price sealed-bid auction. The tests rely on observations of the magnitudes and timings of the top two proxy bids, with the different tests stemming from different regularity assumptions about the underlying distribution of valuation signals. We apply the tests to data from three eBay markets--MP3 players, DVDs, and used cars--and we reject the sealed-bid abstraction in all three data sets. A closer examination of these rejections suggests that they are driven by less experienced bidders. This consistent rejection casts doubt on several existing theories of online auction behavior and suggests some demand estimates based on the abstraction can be biased. To assess the direction and magnitude of this bias, we propose and estimate a new model in which some bidders conform to the abstraction while other bidders bid in a reactive fashion. Because reactive bidding can be at least partially detected from the data, we are able to estimate the underlying distribution of demand and compare it to what the sealed-bid abstraction implies. We find that our proposed model fits the data better, and our demand estimates reveal a large potential downward bias were we to assume the second-price sealed-bid model instead.

Suggested Citation

  • Robert Zeithammer & Christopher Adams, 2010. "The Sealed-Bid Abstraction in Online Auctions," Marketing Science, INFORMS, vol. 29(6), pages 964-987, 11-12.
  • Handle: RePEc:inm:ormksc:v:29:y:2010:i:6:p:964-987

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    References listed on IDEAS

    1. Adams, Christopher P., 2007. "Estimating demand from eBay prices," International Journal of Industrial Organization, Elsevier, vol. 25(6), pages 1213-1232, December.
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    Cited by:

    1. Kannan Srinivasan & Xin Wang, 2010. "Commentary--Bidders' Experience and Learning in Online Auctions: Issues and Implications," Marketing Science, INFORMS, vol. 29(6), pages 988-993, 11-12.
    2. Ernan Haruvy & Peter T. L. Popkowski Leszczyc, 2015. "The Loser’s Bliss in Auctions with Price Externality," Games, MDPI, Open Access Journal, vol. 6(3), pages 1-23, July.
    3. Donna, Javier & Schenone, Pablo & Veramendi, Gregory, 2016. "Frictions in internet auctions with many traders: A counterexample," Economics Letters, Elsevier, vol. 138(C), pages 81-84.
    4. Jason Shachat & Lijia Wei, 2012. "Procuring Commodities: First-Price Sealed-Bid or English Auctions?," Marketing Science, INFORMS, vol. 31(2), pages 317-333, March.
    5. Ernan Haruvy & Peter T. L. Popkowski Leszczyc, 2010. "Search and Choice in Online Consumer Auctions," Marketing Science, INFORMS, vol. 29(6), pages 1152-1164, 11-12.
    6. Robert Zeithammer & Christopher Adams, 2010. "Rejoinder--Causes and Implications of Some Bidders Not Conforming to the Sealed-Bid Abstraction," Marketing Science, INFORMS, vol. 29(6), pages 998-1000, 11-12.
    7. Pownall, Rachel A.J. & Wolk, Leonard, 2013. "Bidding behavior and experience in internet auctions," European Economic Review, Elsevier, vol. 61(C), pages 14-27.
    8. repec:eee:indorg:v:54:y:2017:i:c:p:65-88 is not listed on IDEAS
    9. Taylor, Greg, 2012. "Defensive sniping and efficiency in simultaneous hard-close proxy auctions," Journal of Mathematical Economics, Elsevier, vol. 48(1), pages 51-58.
    10. Kevin Yili Hong & Alex Chong Wang & Paul A. Pavlou, 2013. "How does Bid Visibility Matter in Buyer-Determined Auctions? Comparing Open and Sealed Bid Auctions in Online Labor Markets," Working Papers 13-05, NET Institute.


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