Dear all, I am calculating the integral and the error associated of my histograms, by using this method Double_t A = Impact_mu_A->IntegralAndError(0,100,error_A, ""); std::cout << "Int_A = " << A<< " +- " <<error_A << std::endl; It works well but I got such a big error, for instance this is wha…

Error on a integral

Wile_E_Coyote March 22, 2018, 11:14am 4

Questions about getting events in each bin/checking error bar is correct or not ROOT

Hi, How are you confident that the error is too large or too small ? Do you know the probability distribution of the observed bin content ? What the bin content represents for you ? If the bin content represent counts, and the histogram normalisation is not fixed, the distribution is a Poisson and the estimated error in ROOT is the one assuming the true value of the Poisson is the observed bin count. If you are filling the histogram with weighted counts, then an approximated procedure is us…

How to calculate error in ROOT ROOT

Hi, This simple blog explains why the bin error for weighted histogram is equal to the square root of their the sum of the bin weight square. https://www-zeuthen.desy.de/~wischnew/amanda/discussion/wgterror/working.html Another derivation is also here http://www.hep.uiuc.edu/e687/memos/weight_err.ps Lorenzo

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