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Re: How to determine the WEIGHTS in MPFITFUN for distribution function fit? [message #55765 is a reply to message #55764]

Thu, 06 September 2007 21:43

duxiyu@gmail.com
Messages: 88
Registered: March 2007

Member

> Boy, that's a good question ... Here are some questions for you.
> How do you measure the counts? How sure are you of the number of
> counts?
> If they are truly counts, the errors may be Poisson distributed, yerr
> ~ 1/y. Have you tried this?

Yerr ~ 1/y? Do you means that the keyword WEIGHTS should be 1/y?

> Are you really interested in the standard errors of the parameters, or
> just the parameters? The estimate of the parameters is fairly robust
> with mpfitfun, so the P values are good estimates regardless of the
> estimated error.
>
> If you can't estimate the 1-sigma errors for Y you could always use
> the bootstrap to estimate the P-errors. I've found this very helpful
> - and really easy to do.

Could you explain for me what the bootstrap is?
Is it a IDL procedure or a mathematic method to estimate the P-error?
I cannot find it in the IDL Help files.

Thanks for your reply.

jdu

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[Message index]

		Re: How to determine the WEIGHTS in MPFITFUN for distribution function fit? By: duxiyu@gmail.com on Thu, 06 September 2007 22:26
		Re: How to determine the WEIGHTS in MPFITFUN for distribution function fit? By: duxiyu@gmail.com on Thu, 06 September 2007 21:43
		Re: How to determine the WEIGHTS in MPFITFUN for distribution function fit? By: Craig Markwardt on Thu, 06 September 2007 11:26
		Re: How to determine the WEIGHTS in MPFITFUN for distribution function fit? By: Vince Hradil on Thu, 06 September 2007 06:52
		Re: How to determine the WEIGHTS in MPFITFUN for distribution function fit? By: Vince Hradil on Tue, 11 September 2007 07:15
		Re: How to determine the WEIGHTS in MPFITFUN for distribution function fit? By: Craig Markwardt on Mon, 10 September 2007 22:21

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