# TProfile errors options

## ‘G’ Errors are 1./SQRT(Sum(1/sigma**2)) For example, this would be useful when all Y’s are experimental quantities measured with different precision Sigma_Y.

say i want to evaluate the resolution of a detector, and its dependence on a quantity, say “(Pt_reco - Pt_true)/Pt_true” (and atfter that plot it against Pt, eta or phi),
my question is:
is ‘G’ the right quantity to fit a resolution ? it seems not to depend explicitly on the number of entries used …

thank you very much

Hi,

if you are having 2D data of the spread (Pt-Pt_true) vs pt (or any other quantities) then you can profile them plotting the mean of the spread vs pt using a TProfile with the default error option. The default error option uses the error on the mean ( error = sigma/sqrt(N) )

Lorenzo

hi,