Hi,
Trying to perform a fit of a RooSimultaneousPdf over a RooDataSet with a very low number of events I encountered a problem, which concerns the role of the categories that have no event in the dataset.
I have 3 categories: 1,2,3. In presence of, for example, 1 event, 2 categories of events must be empty. I noticed that calculating the value of the total negative loglikelihood on such a dataset is completely equivalent to calculate the value of the negative loglikelihood obtained with the simple pdf 1.
In other words, the information brought in by the fact that 2 categories of events are empty is not reflected in the total likelihood.
Is there a standard procedure to include this info?
Cheers,
Danilo