I know AUC is supposed to be independent on the threshold, which means AUC does not change while the threshold changes. However, I'm getting different AUC values while changing the thresholds. I'm using
roc_auc_score to calculate the AUC value in Python.
I've got the probability and assigned the group as 1 if the probability is greater than 0.5 and 0 if the probability is less than 0.5. I assume 0.5 is the threshold here? And then I wanted to try with 0.4, 0.3, and so on. The AUC for each case is not supposed to change, but mine was different everytime I used a different threshold.
Is there any idea of why I'm getting different values?