Re: how to re-calculate error matrix in TMinuit

From: X. Lu, Peking Univ. <hsienkuo.lu_at_gmail.com>
Date: Wed, 23 May 2007 21:37:54 +0800

Hi, Arthur,

On 5/14/07, Arthur E. Snyder <snyder_at_slac.stanford.edu> wrote:
>
> What kind of weight are you referring too? There are no explicit weights
> in a maximum likelihood fit.

I am referrring to the event weights, to correct the distribution accroding to the detection efficiency. And
Solmitz's method to correct the weighted error matrix requires another error matrix with
squared weights.

Best Regards,
Xianguo

> -Art S.
>
> PS. Generally, speaking minuit is not going to recompute errors for you
> without rerunning the fit.

A.E. Snyder, Group EC                        \!c*p?/


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>
>
>
> On Sat, 12 May 2007, X. Lu, Peking Univ. wrote:
>
> > Dear Rooter,
> >
> > I have the following question about TMinuit:
> >
> > I have performed a Maximum Likelihood fit using TMinuit, and obtained
> > estimated parameters and errors.
> > Then I want to get a new error matrix by changing some variables (such
> as
> > weight) at the found minimum of the -log likelihood function.
> > How can I do this without performing a new minimization procedure of
> TMinuit
> > ?
> >
> > Thanks in advance !
> >
> > Best Regards,
> > Xianguo
> >
> > --
> > Take flight into the sky, beyond the moon, beyond my mind.
> >
> > Xianguo LU
> > Physics Department, Peking University
> > Beijing, China
> > Tel: 0086-10-62753888(o)
> >
>

-- 
Take flight into the sky, beyond the moon, beyond my mind.

Xianguo LU
Physics Department, Peking University
Beijing, China
Tel: 0086-10-62753888(o)

Received on Wed May 23 2007 - 15:38:03 CEST