A Two-Stage Feature Weighting Method for Naive Bayes and Its Application in Software Defect Prediction

Software defect prediction (SDP) models facilitate software practitioners to find out defect-prone software modules in software. Software practitioners can then test these defect-prone software modules with limited testing resources to minimize software defects. Among various SDP models, Naive Bayes (NB) has been widely used in SDP because of its simplicity, effectiveness and robustness. The NB classifier is an effective classification approach, especially for data sets with discrete attributes. In NB, the attributes are assumed to be independent and thus equally important. However, in common practice, the attributes of software defect data sets are usually continuous or numeric, and because they are designed for different purposes, their contributions to prediction are different. Therefore, this paper proposes a new NB method called TSWNB, which contains two stages: feature (i.e. attribute) discretization and feature weighting. More specifically, for the stage of feature discretization, we make the comparison between two discretization methods i.e. equal-width discretization method and equal-frequency discretization method, and identify the most appropriate one. For the stage of feature weighting, we use the feature weighting technique to alleviate the equal importance assumption, which combines the obtained feature weights into the NB formula and its likelihood estimations. To evaluate the proposed method, we carry out experiments on 5 software defect data sets of NASA MDP provided by PROMISE repository. Three well-known classification algorithms and two feature weighting techniques are included for comparison. The experimental results reveal the effectiveness and practicability of the two-stage feature weighting method TSWNB.