Combining accuracy and prior sensitivity for classifier design under prior uncertainty

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Abstract

Consideringtheclassi¿cationprobleminwhichclasspriorsormisallocationcostsarenotknownprecisely,receiveroperatorcharacteristic(ROC)analysishasbecomeastandardtoolinpatternrecognitionforobtainingintegratedperformancemeasurestocopewiththeuncertainty.Similarly,insituationsinwhichpriorsmayvaryinapplication,theROCcanbeusedtoinspectperformanceovertheexpectedrangeofvariation.InthispaperwearguethateventhoughmeasuressuchastheareaundertheROC(AUC)areusefulinobtaininganintegratedperformancemeasureindependentofthepriors,itmayalsobeimportanttoincorporatethesensitivityacrosstheexpectedprior-range.Weshowthataclassi¿ermayresultinagoodAUCscore,butapoor(large)priorsensitivity,whichmaybeundesirable.Amethodologyisproposedthatcombinesbothaccuracyandsensitivity,providinganewmodelselectioncriterionthatisrelevanttocertainproblems.Experimentsshowthatincorporatingsensitivityisveryimportantinsomerealisticscenarios,leadingtobettermodelselectioninsomecases