Contents I. Introduction
Search engines are the main gateway to the Web. This subject represents the importance of the evaluation of search engine. The most important factor in user satisfaction of search engine, is the relevance of the results provided by it which is measured by precision factor. To the best of our knowledge, the proposed methods in the literature for precision estimation could be seen from different viewpoints. Because a search engine must show a ranked list of results in response to the queries which has be send from user to it. As the documents were returned in the top of the list have the better quality the search engine has the higher precision which is measured by evaluation methods. According to the judgment agent, the evaluation methods could be categorized to automatic evaluation methods [21] [3] and human based evaluation methods [2] [22]–[24]. In fact, an evaluation system consists of three main parts which are the query generation unit, the judgment unit and the unit for criteria computation. The judgment unit is the most important and most expensive part of the evaluation system. Automatic or human based evaluation is related to the implementation of the judgment unit.
