How Important are User-generated Data for Search Result Quality?

Résumé

Do search engines produce better results because their algorithm is better, or because they can access more data from past searches? We document that the algorithm of a small search engine can produce non-personalized results that are of similar quality to the dominant firm’s (Google) if it has enough data. Overall differences in the quality of search results are explained by searches for rare queries. This is confirmed by results from an experiment, in which we keep the search engine algorithm fixed and only vary the amount of data it uses as input.