Good evening dear R-list members, I would like to have your advices on the best way to estimate the theta in a spatial glmmPQL with a correlation structure (such as correlation=corSpher(form=~X+Y)) and a negative.binomial family. Contrary to gam and the negbin family (mgcv), which can estimate theta, the negative.binomial family of MASS requires a fixed value of theta. How am I to specify this value ? Shall I run the model on a range of values for theta and look for one that gets the scale parameter close to 1 (by the way, is it the $sigma in glmmPQL objects ?). Or is there a way to use the different functions in MASS (theta.md, theta.ml) for that purpose ? I could not find anything on the forum pages but hope it is not a too trivial question... Best regards Alexandre Villers PhD. Student Team Biodiversity CEBC CNRS 79360 Beauvoir sur Niort __________ Information from ESET Mail Security, version of virus signature database 4501 (20091012) __________ The message was checked by ESET Mail Security. http://www.eset.com
estimating the "right" theta in a glmmmPQL model with neg bin error family and spatial structure
1 message · alexandre villers