What snippets say about pages

What is the likelihood that a Web page is considered relevant to a query, given the relevance assessment of the corresponding snippet? Using a new FederatedWeb Search test collection that contains search results from over a hundred search engines on the internet, we are able to investigate such research questions from a global perspective. Our test collection covers the main Web search engines like Google, Yahoo!, and Bing, as well as smaller search engines dedicated to multimedia, shopping, etc., and as such reflects a realistic Web environment. Using a large set of relevance assessments, we are able to investigate the connection between snippet quality and page relevance. The dataset is strongly heterogeneous, and care is required when comparing resources. To this end, a number of probabilistic variables, based on snippet and page relevance, are introduced and discussed.