It is well known from the ROC analysis, that in order to achieve the best results, the discovered rules should be as close as possible to the top-left corner of the ROC space. This means that in the TPr/FPr tradeoff, TPr should be as large as possible, and FPr as small as possible. Similarly, in the TP/FP space, TP should be as large as possible, and FP as small as possible.
In this work the quality measure qg = TP/(FP+g) using generalization parameter g has been defined. This section explains why this quality measure has been selected, in comparison with other more intuitive quality measure like a cost-based measure qc involving `cost' parameter c.