Re: TH1::Fit() errors estimation

From: Pasha Murat (murat@cdfsga.fnal.gov)
Date: Tue Jun 30 1998 - 18:57:26 MEST


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.



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