[R-sig-ME] paired and repeated measurements

[Sven Wirthner]

Dear all

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 (see attached table). 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.wirthner at wsl.ch
http://www.wsl.ch

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