From: Martin Maechler <maechler_at_stat.math.ethz.ch>

Date: Fri 02 Dec 2005 - 00:55:45 EST

R-help@stat.math.ethz.ch mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Fri Dec 02 01:00:38 2005

Date: Fri 02 Dec 2005 - 00:55:45 EST

>>>>> "YNoel" == NOEL Yvonnick <yvonnick.noel@uhb.fr> >>>>> on Thu, 01 Dec 2005 14:42:44 +0100 writes:

YNoel> On 11/30/05, Scott Story <sstory@montana.edu> wrote:

>>> I am trying to write a function that will solve a simple system of

* >>> nonlinear equations for the parameters that describe the beta
** >>> distribution (a,b) given the mean and variance.
** >>>
** >>>
** >>> mean = a/(a+b)
** >>> variance = (a*b)/(((a+b)2) * (a+b+1))
** >>>
** >>> Any help as to where to start would be welcome.
*

>>

>>

YNoel> The simplest way to go is probably to use the fitdistr function in MASS
YNoel> package.

yes, definitely for estimating the beta parameters - namely do something smarter than the above moment estimates.

However, I (and probably most respondents to this thread) believe that the question was more general (as the subject indicates) about solving non-lin eq systems, rather than about estimating the beta parameters (by a sub-optimal method).

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https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Fri Dec 02 01:00:38 2005

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