A spreadsheet for calculating the area under an ROC curve for a credit card default model of defaulting credit card customers based on data containing age, years employment, year at address, car debt, and automobile debt. Other parameters calculated are Condition incidence in the Training Set, Base Rate Cost per Event, Incremental value of the model (savings per event), and payback period given the cost per false positive, the cost per false negative, the minimum cost per event, and the threshold at which the minimum cost per event occurs. The model in the spreadsheet obtains an area under the curve of 0.81 and includes the factors years at employer and debt to income ratio.