2. The method of claim 1 , further comprising: identifying, from memory associated with the one or more server devices, additional link selection data for a plurality of additional documents each having a corresponding additional link associated with additional particular feature data, the additional particular feature data identifying one or more additional link attributes of the corresponding additional links, and the additional link selection data indicating an additional quantity of additional user device selections of the corresponding additional links of the documents; wherein generating the measure comprises generating the measure based on the link selection data and the additional link selection data.
2. The method of claim 1 , further comprising: identifying, from memory associated with the one or more server devices, additional link selection data for a plurality of additional documents each having a corresponding additional link associated with additional particular feature data, the additional particular feature data identifying one or more additional link attributes of the corresponding additional links, and the additional link selection data indicating an additional quantity of additional user device selections of the corresponding additional links of the documents; wherein generating the measure comprises generating the measure based on the link selection data and the additional link selection data. 4. The method of claim 2 , wherein the particular feature data identifies the one or more link features associated with the links and identifies features of source documents containing the links or features of the target documents referenced by the links.