Tip: To obtain decision rate matrices for a response using the default profit matrix with costs of 1 and -1, select Specify Profit Matrix from the red triangle menu, make no changes to the default values, and click OK.
 • The Decision Count matrices are in the first row.
 • The Specified Profit Matrix is to the right in the first row.
 • The Decision Rate matrices are in the second row.
 1 Select Help > Sample Data Library and open Liver Cancer.jmp.
 2 Select Analyze > Modeling > Partition.
 3 Select Severity and click Y, Response.
 4 Select BMI through Jaundice and click X, Factor.
 5 Click OK.
 6 Click Split ten times.
Panel Showing Summary of Split
 7 From the red triangle menu next to Partition for Severity, select Specify Profit Matrix.
 8 Change the entries as follows:
Completed Profit Matrix
 ‒ Each value of 1 reflects your profit when you make a correct decision.
 ‒ The -3 value indicates that if you classify a Low severity patient as High severity, your loss is 3 times as much as the profit of a correct decision.
 ‒ The -5 value indicates that if you classify a High severity patient as Low severity, your loss is 5 times as much as the profit of a correct decision.
 9 Click OK.
 10 From the red triangle menu next to Partition for Severity, select Show Fit Details.
Confusion Matrix and Decision Matrix Reports
 11 From the red triangle menu next to Partition for Severity, select Save Columns > Save Prediction Formula.
 ‒ The first three columns involve only the predicted probabilities. The confusion matrix counts are based on the Most Likely Severity column, which classifies a patient into the level with the highest predicted probability. These probabilities are given in the Prob(Severity == High) and Prob(Severity == Low) columns.
 ‒ The last five columns involve the profit matrix weighting. The column called Most Profitable Prediction for Severity contains the decision based on the profit matrix. The decision for a patient is the level that results in the largest profit. The profits are given in the Profit for High and Profit for Low columns.
The Confusion Matrix in Confusion Matrix and Decision Matrix Reports shows classifications based on predicted probabilities alone. Based on these, 33 High severity patients would be classified as Low severity and 5 Low severity patients would be classified as High severity. The Decision Matrix report incorporates the weights in the profit matrix. Using those weights, only 5 High severity patients are classified as Low severity. However, this comes at the expense of misclassifying 38 Low severity patients into the High severity group.