How to consider uncertanities while fitting a histogarm

Newbie
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1

Dear Experts ,

I have a histogram and for each of its bins I have the uncertainties estimated using error propagation, now I would like to fit my histogram with errors. I have the following questions :

  1. If I draw my histogram using the drawing options “E1” and fit, will the uncertainties be considered in root by default if I fit it with a user defined function ?

  2. If not how to consider the uncertainties while making the fit"

Thank you!

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2

Dear Deby,

Thanks for the question.
The relevant piece of documentation can be found here.

The answer is yes, the uncertanties are taken into account unless you specify otherwise :slight_smile:

I hope this helps.

Cheers,
D

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3

Dear Danilo,

Thanks for the response!

But I am not sure whether I have understood you correctly.

Here I attach a macro in which I open a histogram and I want to find its first derivative (for which I do dy/dx, taking 7 bins). And I fit the first derivative in two ways :

  1. I draw histogram without errors and fit using the fit function defined (h2)
  2. I draw histogram with option E1 and fit using the fit function (h4)

And in both the cases I have the same fit results. Which I understand as root always calculates the errors automatically before fitting, Is this so ?

I attach my macro and result herewith for your consideration, thank you.

Cheers,
Deby
check4.C (5.1 KB)
h1.root (2.7 KB)

demo
demo645×880 74 KB

4

Hello,

I think the way in which you decide to draw the histograms have no effect on the uncertainties on the bin content. But perhaps I am misunderstanding the question.

Cheers,
D

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5

I might be wrong, but it seems this thread is similar to this one. (sorry if not)

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