1. A device comprising: a memory to store instructions; and a processor to execute the instructions to: determine, for each document of a plurality of documents, information identifying a measure of quality of the document as a search result for one or more search queries, the information, identifying the measure of quality of a particular document in the plurality of documents, being determined based on: a probability that the particular document will be selected at least a threshold number of times during a particular time period when the particular document is presented as a search result, the probability that the particular document will be selected being based on a position of the particular document in a ranked list of search results, and a probability that the particular document will be presented as a search result at least a threshold number of times during a particular time period, store, in an index, information regarding one or more documents of the plurality of documents based on the measure of quality of each document of the one or more documents, predict, based on the information determined for each document of the plurality of-documents, a measure of quality of at least one other document as a search result for a particular search query, and determine whether to store, in the index, information regarding the at least one other document based on the measure of quality of the at least one other document.