US Patent 9098511 Watch time based ranking

Methods, systems, and apparatus, including computer programs encoded on computer storage media, for ranking search results. One of the methods includes identifying one or more sessions for a query and associating watch times of the respective resources watched in the sessions with the query. One or more watch time signals are calculated for a first resource and the query based on the watch times associated with the query. A first search result responsive to the query is obtained, wherein the first search result identifies the first resource and has an associated score S. A new score S′ is calculated based on a least S and a watch time function, the watch time function being a function of the one or more watch time signals. The new score S′ is provided to a process for ranking search results including the first search result.