This is a SAS/Graph program currently written to plot 2 ROC curves, based on
rating data, on a single set of axes. The program can be modified to plot
a single curve, or more than 2 curves.

* This program does not compute sensitivity or specificity for each curve at
  each cutoff. You will need to do that before running this program.

* Modify the title and title2 statements (for the program and plot) as desired. 

* Be sure to replace "printername" with the name of your printer.

* Remember to enter 1-specificity for "spec_i".

* The "1" and "2" in sens_1 and sens_2 refer to "curve 1" and "curve 2".

* You will need to enter 5 rows of data. Each row corresponds to a different
  cutoff for "test result='diseased'". For example, in the first row, for
  the test result to be "diseased", it must be 5. In the second row, it must be 
  at least 4. In the final row, all cases (i.e. any rating of 1 or greater)
  are considered to have a test result of "diseased".

* Remember that the X-axis is 1-specificity, or the 'false-positive rate'.