I was given a code that generates the statistical or systematic uncertainty of different sub-backgrounds to the total background...(adsbygoogle = window.adsbygoogle || []).push({});

Let's say that the total is [itex]N[/itex] and each sub-background has [itex]N_i, \delta N_i[/itex] number of events andrelativeuncertainty (=err/Nevt) respectively.

What the code does is it evaluates the uncertainty on the total bkg by:

[itex]\delta N = \delta N_1 \frac{N_1}{N} + ... + \delta N_M \frac{N_M}{N}[/itex]

Is that correct?

why not:

[itex]\delta N = \frac{\sqrt{N_1^2 \delta N_1^2 + ... + N_M^2 \delta N_M^2}}{N}[/itex]

?

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# A Statistical uncertainties of sub-backgrounds

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