Learning k-Nearest Neighbor Naive Bayes for Ranking

Accurate probability-based ranking of instances is crucial in many real-world data mining applications. KNN (k-nearest neighbor) [1] has been intensively studied as an effective classification model in decades. However, its performance in ranking is unknown. In this paper, we conduct a systematic study on the ranking performance of KNN. At first, we compare KNN and KNNDW (KNN with distance weighted) to decision trees and naive Bayes in ranking, measured by AUC (the area under the Receiver Operating Characteristics curve). Then, we propose to improve the ranking performance of KNN by combining KNN with naive Bayes (simply NB). The idea is that a naive Bayes is learned using the k nearest neighbors of the test instance as the training data and used to classify the test instance. A critical problem in combining KNN with naive Bayes is the lack of training data when k is small. We propose to deal with it using cloning to expand the training data. That is, each of the k nearest neighbors is “cloned” and the clones are added to the training data. We call our new model instance cloning local naive Bayes (simply ICLNB). We conduct extensive empirical comparison for the related algorithms in two groups in terms of AUC, using the 36 UCI datasets recommended by Weka[2]. In the first group, we compare ICLNB with KNN, NB, NBTree[3], C4.4[4]. In the second group, we compare ICLNB with KNN, KNNDW and LWNB[5]. Our experimental results show that ICLNB outperforms all those algorithms significantly. From our study, we have two conclusions. First, KNN-relates algorithms performs well in ranking. Second, our new algorithm ICLNB performs best among the algorithms compared in this paper, and could be used in the applications in which an accurate ranking is desired.