1. A computer-implemented method, comprising: receiving, at a server device and from a client device, a search query entered on the client device by a user; determining, using the server device, that the user belongs to at least a first population group; determining, using the server device, that at least a first article is responsive to the search query; determining, using the server device, an interest value reflecting an interest of the first population group in the first article, the interest value based on at least one selection of the first article made when the first article was previously presented to at least one member of the first population group in response to an earlier search query identical to the search query; determining, using the server device, a first ranking score for the first article, the first ranking score based at least in part on the interest value; and outputting a search result from the server device to the client device in response to the search query, the first article ranked in the search result according to the first ranking score.
2. The method of claim 1 , wherein determining that the user belongs to the first population group comprises determining, using the server device, demographic data associated with the user.