Working Paper, 2011
This paper demonstrates that a high rank on a search engine result page increases clicks to a web site.
Competition regulators may wish to consider search engine ranking decisions as a potential target for regulation in order to mitigate potential anticompetitive effects of altered search rankings.
Search engines are a major means of finding information and web sites, and a firm’s viability may depend on its visibility on search engines.
Search engine users tend to click through sites returned near the top of a search result page.
Useful sites are often ranked more highly, and it is difficult to determine whether highly-ranked sites are clicked more frequently because they are more useful or simply because they are located near the top of the list of results.
Controlling for site relevance, search engine ranking has a very large effect on the rate at which search engine users clicked through to sites.
All else equal, a site appearing at the top of a page of search results was clicked 5.3 to 26.1 percentage points higher than it was when placed outside of the top three results.
Moving a link from the fourth spot (or lower) in the search rankings typically increased traffic through the search engine to the site by a factor of 6 to 30.
These effects are produced by making the sites more conspicuous on the results page rather than by making a user more willing to click on the link having seen it.