Sven: 1. Try this question on the r-sig-mixwed-models list -- more likely to get good responses there, I think.
2. However, my less expert opinion is that you need a random fence within site term (each fence has it's own ID) co2 ~ treatment + time, rand = ~1|fence/site This assumes time is continuous and not a factor, btw; if time is a factor, I think there may be identifiability problems -- but folks on the mixed models list should be able to provide you better guidance. There may well be better ways to model the covariance structure. Bert Gunter Genentech Nonclinical Biostatistics -----Original Message----- From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On Behalf Of Sven Wirthner Sent: Thursday, January 14, 2010 5:24 AM To: r-help@r-project.org Subject: [R] paired repeated measurements I have the following problem: I measured co2 on 6 paired sites (one grubbed and one non-grubbed fence per site -> grubbing = treatment). These measurements I repeated 15 times over 2 years. So, now my problem is how to analyze these data. I tried the following model: mod1_CO2<-lme(co2~treatment+time,random=~1|site,data=CO2_t1_t15) I think with the random effect I included the paired sample design of my study, but obviously the model does not check for the "repeated measurements" structure of my data. Or in other words, the model assumpt that different sampling dates are independent of each other, but they aren't (since I measured the CO2 15 times on exactly the same spot). So, that's why my question is how can I combine the paired (or nested) design with the repeated measurements in one model??? Thank you for any help Sven -- Sven Wirthner Eidg. Forschungsanstalt für Wald, Schnee und Landschaft WSL Tierökologie Zürcherstrasse 111 CH-8903 Birmensdorf Tel. +41 44 7392 371 Fax +41 44 7392 215 sven.wirth...@wsl.ch http://www.wsl.ch ---------------------------------------------------------------------------- ------- This message was sent using IMP (http://horde.org/imp/) at WSL (http://www.wsl.ch). ______________________________________________ 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. ______________________________________________ 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.