How to get the normalization of a single pdf

I’d like to get the number of events under a pdf. This is easy for an extended fit: I just use RooPdf and and the add the coefficients which reflect the number of entries. But how do you do this with a nonextended fit, when there is only one parameter and no coefficient which reflects the number of events under the pdf?


Hi James,

A non-extended p.d.f. has no concept of an event count. It is a density function normalized to unity. When plotted, the RooAbsPdf projection is multiplied with the number of events of the dataset that was previously drawn on the frame, but that is just for visualization.