Journal of Digital Information Management Mechach Kheira, Zekri Lougmiri, Abdi Mustapha Kamel 13 2 2015 In this paper, we address the problem of selection collections. This is important for locating responses in digital libraries. The aim of methods, which deal with the area of information retrieval, is to reduce the amount of the exchanged messages by selecting the best servers from the beginning of the search. We propose a new function of selection based on statistics. Our function takes into account the relevance degree of documents in order to rank collections. We have implemented and compared our function with other methods. The experimentation have shown that our proposition is very competitive.