Extracting chi2, ndf, and p-value from TH1::Chi2Test

ROOT
1

Hi.

Is it possible to get both chi^2 and ndf from TH1::Chi2Test w/o calling the method twice?

I’m also interested in the p-value, but I see from the implementation that this is easily derived via:

 Double_t prob = TMath::Prob(0.5*chsq, Int_t(0.5*ndf));

Thanks!

–Christos

2

about one month ago we extended the functionality of TH1::Chi2Test.
see: root.cern.ch/root/htmldoc//TH1.html#TH1:Chi2Test

Rene

3

Hi Rene.

[quote=“brun”]about one month ago we extended the functionality of TH1::Chi2Test.
see: root.cern.ch/root/htmldoc//TH1.html#TH1:Chi2Test
[/quote]

Yeah, I saw this already.

I was asking if there was a way to only call once the Chi2Test method (with either of the three options: “”, “Chi2”, “Chi2/ndf”) and be able to access all interesting quantities (chi2, ndf, p-value) with some “getter” methods.

4

Hi Christos,

In the CVS version, I have added a new function TH1::Chi2TestX. See:
root.cern.ch/root/htmldoc//TH1.h … :Chi2TestX

Rene

5

Ah, excellent! Thanks a lot!

–C