1. A computerized method for evaluating the quality of a training base comprising a taxonomy comprising a plurality of categories and a set of training documents, in which method the training base is usable for categorizing documents according to the taxonomy, the method being characterized by the steps of: a. rating training documents on a lower level by associating either of the following predicates to a training document: correct, inbound, outbound, unassigned, b. rating categories on a lower level by determining precision/recall values for each category, c. generating higher level category rating attributes from the lower-level rating steps, by associating one or more of: aa) weak category, bb) existing source/sink relationship between categories, cc) close categories to the categories, d. deriving an overall quality measure for the training base from the higher-level and lower-level rating step, e. determining action proposals to improve the training base as either one or more of: aa) modifying the number of categories by adding a new category or deleting an existing category, or bb) splitting a category in one or more new categories, or cc) merging a category with another one, or dd) modifying the number of training documents of a category by adding or removing some of them.