Sampling a Longer Life: Binary versus One-class classification Revisited

When faced with imbalanced domains, practitioners have one of two choices; if the imbalance is manageable, sampling or other corrective measures can be utilized in conjunction with binary classifiers (BCs). Beyond a certain point, however, the imbalance becomes too extreme and one-class classifiers (OCCs) are required. Whilst the literature offers many advances in terms of algorithms and understanding, there remains a need to connect our theoretical advances to the most practical of decisions. Specifically, given a dataset with some level of complexity and imbalance, which classification approach should be applied? In this paper, we establish a relationship between these facets in order to help guide the decision regarding when to apply OCC versus BC. Our results show that sampling provides an edge over OCCs on complex domains. Alternatively, OCCs are a good choice on less complex domains that exhibit unimodal properties. Class overlap, on the other hand, has a more uniform impact across all methods.