Thank you Simon,
that works well. I had tried previously m1 <-gamm(H ~ Tillage + s(Year, by =Tillage), random=list(Block=~ Tillage), na.action=na.omit, data =mydata, correlation = corARMA(form =~ Year|Tillage/Block, p = 1, q = 0)) and that gave me convergence problems. Thank you! eva Quoting Simon Wood: > eva, > > The problem is that the random effects and correlation structure that > you have specified don't meet the restrictions required by lme (which > gamm calls). You can see this by trying > > M0 <-lme(H ~ Tillage , random=list(Block=~1), na.action=na.omit, data > = mydata, correlation = corARMA(form =~ Year|Tillage, p = 1, q = 0)) > > which will fail because you have multiple observations of Year for > each level of Tillage, and because the random effect and correlation > formulae are incompatible. > > The multiple years problem could perhaps be solved by > corARMA(form =~ Year|Tillage/Block, p = 1, q = 0) > if that makes modelling sense? > > A couple of possible fixes are then... > > M1 <-gamm(H ~ Tillage + s(Year, by =Tillage), > random=list(Tillage=~1,Block=~1), na.action=na.omit, data = mydata, > correlation = corARMA(form =~ Year|Tillage/Block, p = 1, q = 0)) > > or, if you really don't want that r.e. structure, then > > M2 <-gamm(H ~ Tillage + s(Year, by =Tillage)+s(Block,bs="re"), > na.action=na.omit, data = mydata, correlation = corARMA(form =~ > Year|Tillage/Block, p = 1, q = 0)) > > [I've assumed that the mapping between this message and the data you > sent off list is DepVar=H, Treatment=Tillage] > > best, > Simon > > > On 17/02/12 09:35, HERNANDEZ PLAZA, MARIA EVA wrote: >> >> >> HELLO ALL, >> >> I AM GETTING AN ERROR MESSAGE WHEN TRYING TO RUN A GAMM MODEL LIKE >> THE ONE BELOW. >> >> I AM USING R VERSION 2.14.1 (2011-12-22) AND MGCV 1.7-12. >> >> M1<-gamm(DepVar ~ Treatment + s(Year, by =Treatment), >> random=list(Block=~1), na.action=na.omit, data = mydata, correlation >> = corARMA(form =~ Year|Treatment, p = 1, q = 0)) >> >> THIS IS THE ERROR MESSAGE >> >> Error in `*tmp*`[[k]] : attempt to select less than one element >> >> I have 312 observations. I get the error when I introduce the >> correlation structure in the model. I have the same problem even if >> I use /corAR1() /or I set bs=ââ¬ï¿¾crââ¬ï¿¾. I also tried to increase >> the >> number of iterations using the control option, but I find the same >> problem. >> >> Is there any other way in which I could include the correlation structure? >> >> I would appreciate any suggestions >> >> thanks! >> >> eva >> [[alternative HTML version deleted]] >> >> >> >> >> ______________________________________________ >> R-help@r-project.org mailing list >> https://stat.ethz.ch/mailman/listinfo/r-help >> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html >> and provide commented, minimal, self-contained, reproducible code. > > > -- > Simon Wood, Mathematical Science, University of Bath BA2 7AY UK > +44 (0)1225 386603 http://people.bath.ac.uk/sw283 > [[alternative HTML version deleted]]
______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
