**In a nutshell:**

**What is the reason why people smooth ROC Curves?**

When I plot a ROC Curve, the emperical data gives me always a parametric function which looks like stairs going up.

This is due to the fact that you either have:

- a non-continuous tests (e.g.: a medical test which can have 0 -10 full points) . So I could only calculate 10 differnt thresholds, because there are no values like "1.45" .

or:

- even if the data is continuous, there is never a measurement for every value.

**-> actually all ROC functions are parametric**

During my research I found out that there are many different methods to smoothen the graphs (see Figure below). Apparently this is relevant in some cases, but unfortunately I could not find out why exactly?

Does anyone know why?

I want to do a ROCAUC analysis about a medical test with 0-7 full points.

Thank you!

Oli