Normalization (or model?) problem in binned ML simultaneous fit

[StephanH]

Hi @Jacopo,

I could imagine that it’s a problem of plotting bin counts vs. densities. The data are plotted as counts if you don’t do anything, but the PDF might be a density, i.e. it’s normalised by bin width. Let me know if this post helps:

Fitting and plotting variable bins histogram in roofit

Hi @sciencecw, I don’t have time at the moment to read through the notebooks, but here are some ideas concerning the two questions: For the data, you have to decide whether you want to divide by bin width or not, i.e. if you want to plot the bare bin counts or the density of entries. When bin widths change, you have to plot the data density instead of the data counts, but now you cannot use Poisson errors, since they only work for bin counts. PDFs are by definition always densities. Therefo…