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.