From bjorn.robroek at gmail.com  Sat May 28 14:53:21 2011
From: bjorn.robroek at gmail.com (unpeatable)
Date: Sat, 28 May 2011 05:53:21 -0700 (PDT)
Subject: [Rd] Nested design
Message-ID: <1306587201493-3557388.post@n4.nabble.com>

Dear R-users,
I have the following problem. I have performed an experiment for which I
gathered a lot of data which I now want to test. The problem is that I
cannot find an appropriate test in R (I am a starter) and someone might give
me a hand. This is what I have done:
Across three sites (Site), I have laid out five transects (Trans)...meaning
five transects in each sites. In each transect I have five Microhabitats
(MH) which should be regarded as subplots (I think). In each transect, every
MH has the same position (so they are not randomized). I now want to test
the effect of Site and MH (nested in Trans) on my response variables.

This is what I do now: model<-aov(Response~Site*MH+error(Trans/MH))

I get the following output: 

Error: Trans
     Df   Sum Sq  Mean Sq
Site  1 0.030294 0.030294

Error: Trans:MH
     Df  Sum Sq Mean Sq
Site  1 10.8367 10.8367
MH    3  0.2836  0.0945

Error: Within
          Df  Sum Sq Mean Sq F value    Pr(>F)    
Site       2 0.92504 0.46252 11.7304 5.880e-05 ***
MH         4 1.86688 0.46672 11.8370 5.645e-07 ***
Site:MH    8 1.17041 0.14630  3.7105  0.001615 ** 
Residuals 54 2.12917 0.03943                      
---
Signif. codes:  0 ?***? 0.001 ?**? 0.01 ?*? 0.05 ?.? 0.1 ? ? 1 

How do I read this?
Any help appreciated!

BTW: I also tried the lme function: model<-lme(Response~Site*MH,
random=~1|Trans/MH)
but then the output is really complicated.

-----
Dr. Bjorn JM Robroek
Ecology and Biodiversity Group
Institute of Environmental Biology, Utrecht University
Padualaan 8, 3584 CH Utrecht, The Netherlands
Email address: b.j.m.robroek at uu.nl
http://www.researcherid.com/rid/C-4379-2008
Tel: +31-(0)30-253 6091
--
View this message in context: http://r.789695.n4.nabble.com/Nested-design-tp3557388p3557388.html
Sent from the R devel mailing list archive at Nabble.com.



[Rd] Nested design
unpeatable