Hi Zoltan, The goal is to model variation per se not the mean (so a function like var = a + Bx instead of y = a + Bx). Thanks for the suggestion for glmmTMB - I'll look into it.
Best, Jeff ******************************************************** Jeffrey A. Stratford, PhD. Department of Biology and Earth System Sciences 84 W South Street Wilkes University, PA 18766 USA https://sites.google.com/a/wilkes.edu/stratford/ ******************************************************** On Thu, Oct 27, 2022 at 2:30 AM Zoltán Botta-Dukát < botta-dukat.zol...@ecolres.hu> wrote: > Dear Jeff, > > I'm not sure if you want to model mean, with accounting variation, or to > modelling the change of variation along gradient. Note that in most > distribution (Gaussian is an exception) mean and variation are not > independent, and often variation increases with increasing mean. So > choosing the correct distribution may solve the problem when the aim is > modelling the mean. If not, or the aim is modelling variation, by > glmmTMB you can fit models both to mean and variance. > > Best wishes, > > Zoltan > > 2022. 10. 27. 2:25 keltezéssel, Stratford, Jeff írta: > > Hi all, > > > > I have several data sets that relate some ecological phenomenon to a > > gradient (e.g., avian species richness and urbanization, weevil > prevalence > > in acorns and latitude - see > https://linkprotect.cudasvc.com/url?a=https%3a%2f%2fwww.mdpi.com%2f1424-2818%2f13%2f7%2f303&c=E,1,0cKp2p1DFujYtllwpy1B4D8YXPODGboC24UE7K8-WmmQA8SHSMN_KuZ3nqTTyQLyp7oD4zyt2JQqLPfjwQ2yFskgIviy3du5WZOU07vtA2RpKPaH&typo=1). > > > Most > > of these data sets have more variation on one end than the other. I have > > considered quantile regression but this seems inadequate. I would like to > > model variation per se along a gradient. > > > > Is there an R function that models sd or variance along a gradient. I was > > thinking that it would require a moving window of some sorts. > > > > Any suggestions would be appreciated. > > > > Thanks, > > > > Jeff > > ******************************************************** > > Jeffrey A. Stratford, PhD. > > Department of Biology and Earth System Sciences > > 84 W South Street > > Wilkes University, PA 18766 USA > > https://sites.google.com/a/wilkes.edu/stratford/ > > ******************************************************** > > > > [[alternative HTML version deleted]] > > > > _______________________________________________ > > R-sig-ecology mailing list > > R-sig-ecology@r-project.org > > https://stat.ethz.ch/mailman/listinfo/r-sig-ecology > > -- > Botta-Dukát Zoltán Zoltán Botta-Dukát > tudományos tanácsadó scientific advisor > Ökológiai Kutatóközpont Centre for Ecological Research > Ökológiai és Botanikai Intézet Institute of Ecology and Botany > > _______________________________________________ > R-sig-ecology mailing list > R-sig-ecology@r-project.org > https://stat.ethz.ch/mailman/listinfo/r-sig-ecology > [[alternative HTML version deleted]] _______________________________________________ R-sig-ecology mailing list R-sig-ecology@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-ecology
