Roulette sampling for cost-sensitive learning

Abstract

In this paper, we propose a new and general preprocessor algorithm, called CSRoulette, which converts any cost-insensitive classification algorithms into cost-sensitive ones. CSRoulette is based on cost proportional roulette sampling technique (called CPRS in short). CSRoulette is closely related to Costing, another cost-sensitive meta-learning algorithm, which is based on rejection sampling. Unlike rejection sampling which produces smaller samples, CPRS can generate different size samples. To further improve its performance, we apply ensemble (bagging) on CPRS; the resulting algorithm is called CSRoulette. Our experiments show that CSRoulette outperforms Costing and other meta-learning methods in most datasets tested. In addition, we investigate the effect of various sample sizes and conclude that reduced sample sizes (as in rejection sampling) cannot be compensated by increasing the number of bagging iterations. © Springer-Verlag Berlin Heidelberg 2007.