[R] covariance analysis model

Romain Barnard romain.barnard at ese.u-psud.fr
Thu Jun 6 11:59:07 CEST 2002


Dear list users,

I have trouble with covariance analysis.

I measured nitrate concentrations in the soil (NO3) and the percentage of 
legumes (LEG, continuous), affected by 2 different CO2 concentrations (CO2, 
discrete). I suspect that CO2 has an effect on LEG and NO3, but also that 
LEG has an effect on NO3, so this is the formula I wrote to test this:
NO3 ~ CO2 + LEG + CO2:LEG

Will LEG be considered continuous if I use aov(NO3 ~ CO2 + LEG + CO2:LEG) ? 
If not, what model can I use to study simultaneously the effect of discrete 
and continuous factors ?


Thank you

Romain Barnard


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Romain Barnard
Université Paris-Sud XI
Laboratoire Ecologie, Systématique et Evolution
Département Ecologie des Populations et des Communautés
UPRESA CNRS 8079 - Bâtiment 362
F-91405 ORSAY Cedex

romain.barnard at ese.u-psud.fr
Tél. 01 69 15 56 85
Fax 01 69 15 56 96

http://www.ese.u-psud.fr/
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