Defining and Measuring Search Bias: Some Preliminary Evidence


Search engines produce immense value by identifying, organizing, and presenting the Internet´s information in response to users´ queries.  Search engines efficiently provide better and faster answers to users´ questions than alternatives.  Recently, critics have taken issue with the various methods search engines use to identify relevant content and rank search results for users. Google, in particular, has been the subject of much of this criticism on the grounds that its organic search results—those generated algorithmically—favor its own products and services at the expense of those of its rivals.  Much of this criticism has focused on the impact of differences among search engines´ algorithmic methods upon individual websites, and allegations of "bias" in search engine results, in lieu of a conventional consumer-welfare driven antitrust analysis.  The more useful attempts to define “bias" focus upon differences in organic rankings attributable to the search engine ranking its own content (“own-content bias”); that is, a sufficient condition for own-content bias is that a search engine ranks its own content more prominently than its rivals do.  Critics also fail to explore the possibility that differences in search engine algorithms result naturally from the competitive process and generate consumer benefits, as well as the vast economic literature replete with procompetitive justifications for vertical integration.  In this paper, we use a large random sample of search queries to explore empirically the nature of search bias and its potential antitrust implications.  Of course, so-called "bias" is not a sufficient condition for competitive harm as a matter of economics because it can increase, decrease, or have no impact at all upon consumer welfare.  Nonetheless, documenting whether and how much of the alleged bias exists in Google´s and its rivals´ search results can improve our understanding of its competitive implications—that is, whether the evidence of discrimination in favor of one´s own content across search engines is more consistent with anticompetitive foreclosure or competition.  From an antitrust perspective, differences in own-content references across engines fail to indicate consumer harm; to the contrary, it is quite possible—and indeed likely—that these differences imply the existence of intense competition among engines.