1. A method for ranking web documents including user generated content (UGC) with respect to search results generated by a search engine, the search results comprising a set of web documents belonging to a plurality of root categories, the method comprising: recognizing a UGC data field collected from a web document located at a web location, the web document belonging to at least one root category of the plurality of root categories; calculating a document goodness factor for the web document, the document goodness factor measuring overall quality of the web document; calculating an author rank for an author of the UGC data field; calculating a web location rank for the web location; generating a rating factor for the UGC data field based on the document goodness factor, the author rank and the web location rank; boosting the web document in a search result set of web documents to a higher ranking above another web document based on the at least one root category that the web document belongs having more web documents in the result set belonging thereto than the another of the web document in the search set while applying a damping factor in determining whether to boost the web document, the damping factor minimizes penalizing the another web document in the result set as a result of belonging to a root category having less web documents in the result set than the web document, wherein the damping factor is a function of a difference between a number of documents in a first category and a number of documents in a second category divided by a total number of documents in at least the first and the second categories; and outputting a search result including the UGC data field positioned in the search results based on the rating factor and the damping factor.