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A welfare analysis of "junk" information and spam filters


  • Josef Falkinger

    () (Socioeconomic Institute, University of Zurich)


This paper analyses the equilibrium effects of individual information filters. Information is modelled as advertisements which are distributed across a population of consumers with heterogeneous preferences. An advertisement that provides knowledge about a product with little or no utility for a consumer is considered junk. Filters are characterised by their level of tolerance. The quality of the filter is measured in terms of the share of useful items in the total set of items passing the filter. It is shown that in conditions of decentralised competition, multiple equilibria arise. A social optimum can be achieved by demanding each consumer to reject a certain percentage of advertisements, leaving the choice of what is rejected up to the consumer him/herself.

Suggested Citation

  • Josef Falkinger, 2008. "A welfare analysis of "junk" information and spam filters," SOI - Working Papers 0811, Socioeconomic Institute - University of Zurich.
  • Handle: RePEc:soz:wpaper:0811

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    References listed on IDEAS

    1. Falkinger, Josef, 2007. "Attention economies," Journal of Economic Theory, Elsevier, vol. 133(1), pages 266-294, March.
    2. S. A. Ozga, 1960. "Imperfect Markets Through Lack of Knowledge," The Quarterly Journal of Economics, Oxford University Press, vol. 74(1), pages 29-52.
    3. Dixit, Avinash K & Stiglitz, Joseph E, 1977. "Monopolistic Competition and Optimum Product Diversity," American Economic Review, American Economic Association, vol. 67(3), pages 297-308, June.
    4. Falkinger, Josef, 2005. "Limited Attention as the Scarce Resource in an Information-Rich Economy," IZA Discussion Papers 1538, Institute for the Study of Labor (IZA).
    5. Gerard R. Butters, 1977. "Equilibrium Distributions of Sales and Advertising Prices," Review of Economic Studies, Oxford University Press, vol. 44(3), pages 465-491.
    6. Josef Falkinger, 2008. "Limited Attention as a Scarce Resource in Information-Rich Economies," Economic Journal, Royal Economic Society, vol. 118(532), pages 1596-1620, October.
    7. George J. Stigler, 1961. "The Economics of Information," Journal of Political Economy, University of Chicago Press, vol. 69, pages 213-213.
    8. Bagwell, Kyle, 2007. "The Economic Analysis of Advertising," Handbook of Industrial Organization, Elsevier.
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    Cited by:

    1. Simon P. Anderson & André de Palma, 2012. "Competition for attention in the Information (overload) Age," RAND Journal of Economics, RAND Corporation, vol. 43(1), pages 1-25, March.

    More about this item


    global information society; advertising; junk information; spam filter; Internet regulation;

    JEL classification:

    • D83 - Microeconomics - - Information, Knowledge, and Uncertainty - - - Search; Learning; Information and Knowledge; Communication; Belief; Unawareness
    • L86 - Industrial Organization - - Industry Studies: Services - - - Information and Internet Services; Computer Software
    • M38 - Business Administration and Business Economics; Marketing; Accounting; Personnel Economics - - Marketing and Advertising - - - Government Policy and Regulation
    • D18 - Microeconomics - - Household Behavior - - - Consumer Protection

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