JNCC 2 user manual and tutorial ( rev 1 )

This paper introduces JNCC2, the Java implementation of the Naive Credal Classifier 2 (NCC2). JNCC2 is open source; it is hence freely available together with manual, sources and javadoc documentation. NCC2 is an extension of Naive Bayes Classifier (NBC) to imprecise probabilities, designed so as to return robust classifications even on small and/or incomplete data sets. A peculiar feature of NCC2 is that it returns indeterminate classifications (i.e., more than one class) when faced with doubtful instances. The empirical results of Corani and Zaffalon (2008) have shown that NCC2 returns indeterminate judgments on instances whose classification is truly doubtful; in fact, NBC achieves a much higher classification accuracy on the instances precisely classified by NCC2, than on those indeterminately classified by NCC2.