Characteristics of Accuracy and Coverage in Rule Induction

Rough set analysis are closely related with accuracy and coverage. However, there have been few studies on the formal characteristics of accuracy and coverage for rule induction have never been discussed until Tsumoto showed several characteristics of accuracy and coverage. In this paper, the following characteristics of accuracy and coverage are further investigated: (1) The higher the accuracy of the conjunctive formula become, the lower the effect on the conjunction will become. (2) Coverage will decrease more rapidly than accuracy. (3) The change of coverage becomes very small when the length of the conjunctive formula becomes larger. (4) The discussions above are corresponding to those on sensitivity and specificity. (5) When we focus on accurate classification, the classification efficiency, which is the product of sensitivity and specificity will become lower.