Hi all,
I would like to combine efficiencies (using TEfficiency::Combine) from different channels, with an external weight for each. I provide an example of the observed behaviour in the little program attached (tefficiency.cc). In this file, a desired weight of 1 for each channel is taken.
I compute efficiencies from MC and apply a weight from data for each of the channels. I then would like to compute the combined efficiency on the merged channels to apply it on data, with a correct estimate of the error on it.
From the ROOT code (see root.cern.ch/root/html534/src/TE … .html#1727), it seems that the combination takes the total numbers of events for each channel as implicit weights between the different channels.
To correct for this effect for my use case, I set the weights with a reweighting for the number of total events of each channel. If I don’t do it, the result is not the expected one (the electron example of the documentation can here be misleading).
Is this reweighting the correct way to proceed in my case ?
Moreover, the central value of the combined efficiency, even with reweighting by the number of entries, is slightly different from the central value with the same equivalent case. Is it expected ?
What is the correct way to estimate the error on the combined efficiency ?
Thank in advance for any help !
Thierry
tefficiency.cc (1.7 KB)