Logistic regression with BIC: what is my sample size?

I'd like to compare logistic regression models using the BIC. I have 600 data points, but only 30 of these belong to the class of interest. To calculate the BIC I need to know my sample size, $N$.

In my case, is my sample size 600 or 30? Should the BIC calculation use the total size of my dataset (600), or just the number of positive samples (30)?

• BIC, AIC look at all your data.
– Jon
Dec 18 '16 at 4:34
• How many points did you train your classifier on? This is your sample size. Jun 21 '18 at 11:56

If you have used all 600 points when fitting your model, then the sample size $n$ is 600.