[R] GAM: Remedial measures

[Tim F Liao]

Jean,

The standard treatment of overdispersed data when using the
Poisson distribution to model count data is to switch to the
negative binomial distribution.  Hope this helps,

Tim Liao

---- Original message ----
>Date: Thu, 13 Jan 2005 18:22:29 -0500
>From: "Jean G. Orelien" <jorelien at scimetrika.com>  
>Subject: [R] GAM: Remedial measures  
>To: <r-help at stat.math.ethz.ch>
>
>I fitted a GAM model with Poisson distribution to a data with
about 200
>observations.  I noticed that the plot of the residuals
versus fitted values
>show a trend.  Residuals tend to be lower for higher fitted
values. Because,
>I'm dealing with count data, I'm thinking that this might be
due to
>overdispersion.  Is there a way to account for overdispersion
in any of the
>packages MGCV or GAM?  
>
> 
>
>I welcome any suggestions that one may have on this topic.
>
> 
>
>Jean
>
> 
>
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