Re: [R] quasi glm start values

From: Prof Brian Ripley <ripley_at_stats.ox.ac.uk>
Date: Fri 05 May 2006 - 02:41:56 EST

On Thu, 4 May 2006, Lucy Crooks wrote:

> Hi,
> I'm tying to fit a glm using quasi with variance=mu(1-mu) (to try and
> get "well behaved" residuals). I get an error message:
> "cannot find valid starting values, please specify some".
> I have tried using start= and specifying coefficients from a previous
> fit (with different error structure) but get the same message.
> What would be valid starting values?

What link are you using? You need 0 < mu < 1 (the actual function used is

                validmu <- function(mu) all(mu>0) && all(mu<1)
plus any restriction from the unspecified link).

> I am using a 64 bit build R on a MacG5.

The version of R is more important here.

-- 
Brian D. Ripley,                  ripley@stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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Received on Fri May 05 02:46:55 2006

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