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Google's Exclusive Flight Search OneBox

April 15, 2013 - with Zhenyu Lai


Google often shows “OneBox” search results promoting its own services. These results have prompted antitrust scrutiny: Google awards these preferred placements exclusively to Google's own services, such as Google Flight Search and Google Maps, but never to competing services such as Kayak or Mapquest. Moreover, Google presents OneBox with special format, including distinctive layouts, extra images, and even in-page interactivity – benefits not available to ordinary listings for other sites. Regulators and competitors sense that these exclusive practices can undermine competition and innovation by denying traffic to would-be competitors. But how large is the effect? How much does Google's exclusive OneBox placement impact search engine traffic to adjacent online markets?

In a working paper, Zhenyu Lai and I measure the impact of OneBox by using a quasi-experiment before and after the introduction of Google Flight Search. Using a third-party data service, we compare user behavior on searches across thousands of search queries like “cheap flights from sfo to san ” (which displayed a OneBox for Google Flight Search), and similar search queries like “cheaper flights from sfo to san” (emphasis added) (which did not display OneBox). We find that Google's display of Flight Search in an exclusive OneBox decreased user click-through rates on unpaid search results by 65 percent, and increased user click-through rates on paid advertising links by 85 percent. This effect was disproportionately evident among online travel agencies that were popular destinations for affected search queries.

Our draft provides detailed empirical results as well as a model of how a search engine's incentives to divert search depend on consumers' perceptions of the difference between non-paid and paid placements.
    Exclusive Preferential Placement as Search Diversion: Evidence from Flight Search and data appendix