Collaboration allows integrating knowledge from every participant to achieve individual or collective goals. Thanks to informational environments, we can better organize, realize and record collaboration. Every activity produces a set of traces. With the help of a model of competency, traces contribute to evaluate the competency of users on a certain subject. In this article, we propose a semantic model of traces and analyze classified traces by means of a Bayes classifier. We exploit the results to offer users recommendations and decision aid.