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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