TOMBoost: a topic modeling based boosting approach for learning with class imbalance

Classification of data with imbalanced characteristics is an essential research problem as the data from most real-world applications follow non-uniform class proportions. Solutions to handle class imbalance depend on how important one data point is versus the other. Directed data sampling and data-level cost-sensitive methods use the data point importance information to sample from the dataset such that the essential data points are retained and possibly oversampled. In this paper, we propose a novel topic modeling-based weighting framework to assign importance to the data points in an imbalanced dataset based on the topic posterior probabilities estimated using the latent Dirichlet allocation and probabilistic latent semantic analysis models. We also propose TOMBoost, a topic modeled boosting scheme based on the weighting framework, particularly tuned for learning with class imbalance. In an empirical study spanning 40 datasets, we show that TOMBoost wins or ties with 37 datasets on an average against other boosting and sampling methods. We also empirically show that TOMBoost minimizes the model bias faster than the other popular boosting methods for class imbalance learning.