9. A computer-implemented method, the method comprising: determining a first count of user selections, received by a search engine, of search results that were presented in response to queries that are categorized as referring to a particular site; determining a second count of user selections, received by the search engine, of search results that identify resources in the particular site; and determining a site quality score for the particular site including computing a ratio of a numerator based on the first count and a denominator based on the second count, wherein (i) the numerator is based on the first count reduced by a threshold value which is a predetermined threshold value, (ii) the denominator is based on the second count raised to a power that is greater than zero and less than one, or (iii) both.
13. The method of claim 9 , wherein the user selection of a search result is an action received from a user that causes the resource identified by the search result to be presented, at least in part, to the user.