Re: [R] offset in gam and spatial scale of variables

Hi, Thanks for the inputs. I talked to my coworker, who has been the one doing the analysis. Perhaps I wasn't making myself clear about the “differences in spatial scales”. Here is what he says: The truth is that measuring scales (i.e all area related variable are measured in m2) and spatial

Re: [R] offset in gam and spatial scale of variables

On Thu, May 20, 2010 at 3:20 PM, Lucia Rueda lucia.ru...@ba.ieo.es wrote: Hi, Thanks for the inputs. I talked to my coworker, who has been the one doing the analysis. Perhaps I wasn't making myself clear about the “differences in spatial scales”. Here is what he says: The truth is that

[R] offset in gam and spatial scale of variables

Hi, We are analizing the relationship between the abundance of groupers in line transects and some variables. We are using the quasipoisson distribution. Do we need to include the length of the transects as an offset if they all have the same length?? Also, can we include in the gam models

Re: [R] offset in gam and spatial scale of variables

Could you specify the package you use? If it is mgcv, this one centers your variables before applying the smooths. That's something to take into account when comparing different models. In any way, If scales are too different, I try rescaling by either : expressing things in different units

Re: [R] offset in gam and spatial scale of variables

Could you specify the package you use? If it is mgcv, this one centers your variables before applying the smooths. That's something to take into account when comparing different models. In any way, If scales are too different, I try rescaling by either : - expressing things in different units

Re: [R] offset in gam and spatial scale of variables

On Wednesday 19 May 2010 15:29, Joris Meys wrote: Could you specify the package you use? If it is mgcv, this one centers your variables before applying the smooths. That's something to take into account when comparing different models. --- er, actually it only centres variables in this way for

Re: [R] offset in gam and spatial scale of variables

We are analizing the relationship between the abundance of groupers in line transects and some variables. We are using the quasipoisson distribution. Do we need to include the length of the transects as an offset if they all have the same length?? --- not just for fitting, I suppose: although

Re: [R] offset in gam and spatial scale of variables

Hi Joris, We're using mgcv. We have data on abundance of groupers on line transects that have the same legth. My coworker has selected a bunch of variables and he has calculated them in terms of total area in different sizes of buffers around the centroid of the transect. He has run gam models

Re: [R] offset in gam and spatial scale of variables

Thank you for the correction. I was thinking about the difference of using a variable with a smoother, and comparing that to a model with that variable without smoother. I should specify that I mostly use thin plate regression splines. If the spline itself is not deviating from linearity, you get

Re: [R] offset in gam and spatial scale of variables

On Wed, May 19, 2010 at 4:51 PM, Lucia Rueda lucia.ru...@ba.ieo.es wrote: Hi Joris, We're using mgcv. We have data on abundance of groupers on line transects that have the same length. I only now realized groupers are actually fish :-). Should work on my english skills... My coworker