Dear Lei,
Perhaps the discussion of ROOT bug #19497 answers your question.
cheers,
Amnon
Dear ROOTors,
According to my study, I need to get the error of the mean value of a weighted histogram.
I have checked the code for calculating this error:
(from the root web) // mean error = RMS / sqrt( Neff )
The Neff is: (sum of Wt)^2 / sum of Wt^2
// s[1] sum of squares of weights, s[0] sum of weights
return (s[1] ? s[0]*s[0]/s[1] : TMath<http://root.cern.ch/root/html/TMath.html>::Abs<http://root.cern.ch/root/html/TMath.html#TMath:Abs>(s[0]) );
Since I am not an expert on statistics, may I ask how this definition come? Where can I find some reference for this formula?
Thank you in advance
Best regards
Lei Received on Thu Feb 23 2012 - 09:21:28 CET
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