Sorry for bothering you - but I have a little problem. I`m completely new in R and trying to use lmer. That works, but I m not sure if my code is right, so I would just like to get an opinion from the experts. I have a Growthrate of plants (RGR Fixed Factors: Fertilizer, Status (alien or native plants) and their interaction Random Factors: Age is a covariable; than I have plantfamily and Species nested within Family. Now I want also to test for the interaction of Fertilizer with plantfamily and species. Did I do this the right way, and is the 0+ necessary? model<-lmer(RGR~Fertilizer+Status+Fertilizer:Status+(1|Age)+(1|Family/Species)+(0+Fertilizer|Family/Species),data=rgr) I`m thankful for any comments! anne -- Anne Kempel Institute of Plant Sciences University of Bern Altenbergrain 21 CH-3103 Bern kempel at ips.unibe.ch