Hi! Something funny happens to me in lnme. I don't know if it's a bug or not. Here's a short sketch of the problem (you could skip the introduction and just go to the models):
I'm counting the number of spider webs ( = response variable) along two rivers, with a two-level treatment: free-flowing and dammed. There are three field sites (random factor) along each river, and measurements are done six times (= random factor for repeated measurements). Webs are counted on four different distances along the river (fixed effect), with six plots at each distance. My model looks like this: * Model<-lme(Webslog1~Treatment*Distance,random=~Week|Uniquesite/Uniqueplot,method="REML") * I want to leave out the interaction between Treatment and Distance, so that would go like this: * >ModelNoInteraction<-lme(Webslog1~Treatment+Distance,random=~Week|Uniquesite/Uniqueplot,method="REML") * However, then i get the error message:* "Error in model.frame.default(formula = ~Week + Webslog1 + Treatment + : invalid type (list) for variable 'Distance' "* I first thought that it is for some reason just not allowed to leave out the interaction. But when i try to run the first model again, i get the same error message! Therefore i thought the thing could be a bug. The whole thing looks like this: *> Model<-lme(Webslog1~Treatment*Distance,random=~Week|Uniquesite/Uniqueplot,method="REML") > ModelNoInteraction<-lme(Webslog1~Treatment+Distance,random=~Week|Uniquesite/Uniqueplot,method="REML") Error in model.frame.default(formula = ~Week + Webslog1 + Treatment + : invalid type (list) for variable 'Distance3' > Model<-lme(Webslog1~Treatment*Distance,random=~Week|Uniquesite/Uniqueplot,method="REML") Error in model.frame.default(formula = ~Week + Webslog1 + Treatment + : invalid type (list) for variable 'Distance3'* *>* Someone any idea? Bug or just my poor R skills? Thanks for having a look at this! Pieter [[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.