1. A method performed by one or more devices, the method comprising: determining, by one or more processors of the one or more devices, an amount or rate that a document moves positions in search result rankings over time, compared to one or more prior positions of the document in the search result rankings; generating, by one or more processors of the one or more devices, a score for the document based on the amount or rate that the document moves in the search result rankings over time, compared to the one or more prior positions of the document in the search result rankings; and ranking, by one or more processors of the one or more devices, the document with regard to at least one other document based on the score.
2. The method of claim 1 , where determining the amount or rate that the document moves in search result rankings includes: determining a number of positions that the document moves in the search result rankings, and where generating the score for the document includes generating the score based on the determined number of positions that the document moves in the search result rankings.