[R] gamcheck doubts

[Simon Wood]

Thanks for the off list plot. I don't see anything untoward in the 
residual plots here - a good way of getting a feel for what residual 
plots should look like if the model is ok, is to simulate some data from 
your fitted model using rnbinom and the fitted values, refit the model 
to the simulated data, and take a look at the resulting residual plots. 
Doing this a few times gives you a feel for the range of plots to expect 
if everything is ok.

best,
Simon

On 06/12/12 06:21, Tania Mendo Aguilar wrote:
> Dear All,
>
> I am fitting scallop count data to negative binomial GAMs. I have two significant parameters that explain 43%of the deviance. The adjusted r square is 0.25. The gam.check function gives me the figure attached. In the graph of linear predictor vs. residuals there seems to be more negative residual values than positive. Is that telling me that the fit is underestimating the response? Can I accept this model?
>
>
> Tania Mendo
> PhD Candidate | Institute for Marine and Antarctic Studies (IMAS)
> University of Tasmania
>
>
>
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-- 
Simon Wood, Mathematical Science, University of Bath BA2 7AY UK
+44 (0)1225 386603               http://people.bath.ac.uk/sw283