Re: [R] Problems using gamlss to model zero-inflated and overdispersed count data: the global deviance is increasing

2010-06-03 Thread Gavin Simpson
On Wed, 2010-06-02 at 13:45 +0200, Joris Meys wrote: Hi Diederik, I can't say immediately why your models fail without seeing the data and running a number of tests. You could play around with the other parameters, as the problem might be related to the optimization algorithm. A different

Re: [R] Problems using gamlss to model zero-inflated and overdispersed count data: the global deviance is increasing

2010-06-03 Thread Joris Meys
On Thu, Jun 3, 2010 at 9:27 AM, Gavin Simpson gavin.simp...@ucl.ac.ukwrote: vegan is probably not too useful here as the response is univariate; counts of ducks. If we assume that only one species is counted and of interest for the whole research. I (probably wrongly) assumed that data for

Re: [R] Problems using gamlss to model zero-inflated and overdispersed count data: the global deviance is increasing

2010-06-03 Thread Gavin Simpson
On Thu, 2010-06-03 at 17:00 +0200, Joris Meys wrote: On Thu, Jun 3, 2010 at 9:27 AM, Gavin Simpson gavin.simp...@ucl.ac.ukwrote: vegan is probably not too useful here as the response is univariate; counts of ducks. If we assume that only one species is counted and of interest for the

Re: [R] Problems using gamlss to model zero-inflated and overdispersed count data: the global deviance is increasing

2010-06-03 Thread Joris Meys
See below. On Thu, Jun 3, 2010 at 5:35 PM, Gavin Simpson gavin.simp...@ucl.ac.ukwrote: On Thu, 2010-06-03 at 17:00 +0200, Joris Meys wrote: On Thu, Jun 3, 2010 at 9:27 AM, Gavin Simpson gavin.simp...@ucl.ac.uk wrote: vegan is probably not too useful here as the response is

Re: [R] Problems using gamlss to model zero-inflated and overdispersed count data: the global deviance is increasing

2010-06-03 Thread Joris Meys
Correction : That should give some clarity on the question whether it is the optimization of GAMLSS that goes wrong, or whether the problem is inherent to the data. On Thu, Jun 3, 2010 at 7:00 PM, Joris Meys jorism...@gmail.com wrote: See below. On Thu, Jun 3, 2010 at 5:35 PM, Gavin Simpson

[R] Problems using gamlss to model zero-inflated and overdispersed count data: the global deviance is increasing

2010-06-02 Thread Strubbe Diederik
Dear all, I am using gamlss (Package gamlss version 4.0-0, R version 2.10.1, Windows XP Service Pack 3 on a HP EliteBook) to relate bird counts to habit variables. However, most models fail because “the global deviance is increasing” and I am not sure what causes this behaviour. The dataset

Re: [R] Problems using gamlss to model zero-inflated and overdispersed count data: the global deviance is increasing

2010-06-02 Thread Joris Meys
Hi Diederik, I can't say immediately why your models fail without seeing the data and running a number of tests. You could play around with the other parameters, as the problem might be related to the optimization algorithm. A different approach would be using the methods in the vegan package.