Problems with Fit Options Statistics Panel

Newbie
1

Hello everyone,

I am having a problem with the statistics panel of my fit. I am trying to fit the same function in my spectrum with different ranges but even though I change the range, my fit parameters, chi-square / ndf and etc don’t change in the fit statistics panel but if I ask to print in the terminal, using for example:

  cout << "Chi Square = " << f4->GetChisquare() << endl;
  cout << "NDF  = " << f4->GetNDF() << endl;

then I obtain a different chi-square that I have in the statistic panel.

Can anybody help me?

Sorry if this problem already appeared here, but I couldn’t find anything that can help me.

Best regards.

2

Hi @rrramos; I am inviting @jonas as he may know the answer to this question.

Cheers.

3

Hi,
Probably, since you are doing many fits with different ranges, the results refer to different fit results.
The best, is for each fit, you keep the TFitResult object , return by TH1::Fit when using option S.
You can then always add the desired values in the fit statistics panel.

Lorenzo

4

After each “Fit” statement, try to add:
if (gPad) { gPad->Modified(); gPad->Update(); }

5

Hi Lorenzo,

when you say it, it’s for example, to me to do something like that:

h1->Fit("f4", "S");

?

and I am doing many fits but it’s not at the same time in my script. Actually, I run my script for each new range because of this I can’t understand why my fits in the statistics panel keep showing the same results, since they are independent.

thank you so much for helping me!!

6

Hi Wile!

I tried to do this but still doesn’t work =/ and also I am not doing each fit in the same time in my scrip, actually I run my script for each new range fit and save the results, because of this I cant understand why the results is the same even when I change the range, also, the Chi square and NDF make no sense for me, because I fiting 4 bins with a function that have 2 parameters (and the fit looks good for me) and I got a Chi square/NDF = 29.13/11. What do you think it can be?

Thank you so much for helping me!

7

Attach your macro for inspection.

8

now that I went to send you my code I ended up finding my error. I was doing this:

 initial->Fit("f1", "REM0");
  initial->Fit("f2", "REM0");
  initial->Fit("f3", "REM0");
  initial->Fit("f4", "REM0");
  initial->Fit("f5", "REM0");
  initial->Fit("f6", "REM0");
  initial->Fit("f7", "REM0");
  initial->Fit("f8", "REM0");
  initial->Fit("f9", "REM0");

I forgot to comment on all these lines that make the fit (how a said, I run only one fit per time, so I think I should let just the line that makes the fit that I want).

Doing this my Chi-square / ndf in the statistics panel is equal to that I print in the terminal using this

  cout << "Chi Square = " << f4->GetChisquare() << endl;
  cout << "NDF  = " << f4->GetNDF() << endl;

With these, my problem is solved!!

Thank you!!!

9

Hi Lorenzo, I found my error in the code, now my problem is solved! Thank you for your help!!