Re: TH1::Fit() errors estimation
Pasha Murat (murat@cdfsga.fnal.gov)
Tue, 30 Jun 1998 11:57:26 -0500 (CDT)
Tadeusz Pytlos writes:
> Hello Rooters,
> I didn't find on ROOT WWW pages, what errors are taken
> into fitting of histogram. I understand that defaultly
> x is taken as bin center, sx is a half of bin width (?),
> y is a hight of bin, but what with sy. Is sy
> sqrt(hight_of_bin)? There seems to be tree possibilities
> in fit options:
> ""
> "W" Set all errors to 1 (that's seems to be clear)
> "E" Minos technique
> Would you be so nice to tell me what is meaning of default settings
> and mysterious Minos technique?
> Thank you in advance,
> Tadeusz
MINOS is a minimization algorithm implemented in MUNUIT,
it takes into account non-parabolic behaviour
of the minimized function in the vicinity of the minimum,
so the errors it reports are asymmetric.
For more details see MINUIT manual (available from CERN documentation
cite http://wwwcn.cern.ch/asdoc/Welcome.html).
regards, pasha.