ROC/AUC and Cut off point

[Omar Zahaf]

Dear all

I am trying to design a ROC curve and find the optimal cut off point.
My reference variable is "CardiacD" where 0 is "Heart disease" and 1 is "Valve Disease"
My class variable is "meanagreedvalue" which is a continuous variable.

I am trying to create a ROC CURVE and find the optimal cut off point for "meanagreedvalue" that will help differentiate between Heart disease and Valve disease.

The data is all normally distributed.

My code is :
rocreg CardiacD meanagreedvalue, probit

But when I plot this, I get a totally inverse ROC curve than what I am expecting:




This does not quite make sense to me but I am not sure what mistake I have made.


For the optimal cutoff point I have used the cutpt command

cutpt CardiacD Meanagreedvalue, noadjust


Many thanks in advance and greatly appreciated.

[Omar Zahaf]

Apologies, here is the ROC curve that does not make sense to me

[Joseph Coveney]

replace meanagreedvalue = -meanagreedvalue
rocreg CardiacD meanagreedvalue