Hi there,

Firstly, I just wanted to say thank you for taking time to read this post.

I have performed roctab on the independent variable x and the dependent variable z. I have also performed roctab on another independent variable y and the dependent variable z. I want to overlay the ROC curves on top of each other. I have tried using roccomp which has so far been unsuccessful. I believe this is because I have a different number of observations for variables for x and y. It appears roccomp only uses the observations which have values for both x and y, leading to different AUC values as to what is calculated by the roctab command for each variable x and y.

Is there a way I can overlay the roctab graphs by not losing observations using roccomp?

Regards, your help is much appreciated.

Jimmy

Code:
roctab z x
roctab z y
roccomp (z x y)