MedCalc  # Comparison of ROC curves

 Command: Statistics ROC curves Comparison of ROC curves

## Description

Use Comparison of ROC curves to test the statistical significance of the difference between the areas under 2 to 6 dependent ROC curves (derived from the same cases) with the method of DeLong et al. (1988) or Hanley & McNeil, 1983.

## Required input

In the dialog box you need to enter: Data

• Variables: select the variables of interest (at least 2, maximum 6).
• Classification variable: select a dichotomous variable indicating diagnosis (0=negative, 1=positive).

If your data are coded differently, you can use the Define status tool to recode your data.
• Filter: (optionally) a filter in order to include only a selected subgroup of cases (e.g. AGE>21, SEX="Male").

Methodology:

• DeLong et al.: use the method of Delong et al. (1988) for the calculation of the Standard Error of the Area Under the Curve (AUC) and of the difference between two AUCs (recommended).
• Hanley & McNeil: use the methods of Hanley & McNeil (1982, 1983) for the calculation of the Standard Error of the Area Under the Curve (AUC) and of the difference between two AUCs.
• Binomial exact Confidence Interval for the AUC: calculate exact Binomial Confidence Intervals for the Area Under the Curves (AUC) (recommended). If this option is not selected, the Confidence Intervals for the AUCs are calculated as AUC ± 1.96 SE (Standard Error). This option does not apply to the difference between two AUCs).

Graph

• Select Display ROC curves window to obtain the ROC curves in a separate graph window.

Option:

• mark points corresponding to criterion values.

When you have completed the dialog box, click OK to proceed.

## Results

The results window shows the data for the different ROC curves followed by the result of pairwise comparison of all ROC curves: the difference between the areas, the standard error, the 95% confidence interval for the difference and P-value. If P is less than the conventional 5% (P<0.05), the conclusion is that the two compared areas are significantly different. ## Display Roc curves

When you have selected Display ROC curves window in the dialog box, the program will also open a graph window with the different ROC curves. ## Literature 