## Question

Meaning of negative AUC (in Round 1 results)

Dr. Ballings,

I noticed that some groups have got a negative AUC in the round 1 results.

But, if AUC is Area Under the Curve it should never be negative ...

The help text also says that the return value of AUC::auc function is : "A numeric value between zero and one denoting the area under the

curve"

Could you please explain what a negative AUC indicates?

-Thanks,

Tapajit

## Answers and follow-up questions

** Answer or follow-up question 1** Tapajit,

Thank you for this excellent question.

Indeed AUC is a score between 0 and 1 (and it is always >= 0.5 if you are not overfitting the data).

Scores lower than 0 are impossible.

The problem with those two groups is that they did not submit 300 scores.

For example, if a group submits only 100 values, this means there are 200 NULL values in the database.

The AUC will be computed on 300 scores (in the submission system) and the NULL values are messing up the calculation.

Please note that I programmed the calculation in SQL (I am not using the AUC R package).

So whenever you see a negative AUC on the ranking page it means those groups did not submit 300 scores.

Michel Ballings

Sign in to be able to add an answer or mark this question as resolved.