[R] nested design

[Jörn Buse]

Hello,

there is a problem to calculate the following model:

model<-aov(Biomass~Beech+Age+Error(Age/Stand))

Warning message:
Error() model is singular in: aov(Biomass ~ Beech + Age + Error(Age/Stand))

The summary output is:


Error: Age
      Df Sum Sq Mean Sq
Beech  1 142671  142671

Error: Age:Stand
          Df Sum Sq Mean Sq F value Pr(>F)
Beech      1   4042    4042  0.1123 0.7416
Residuals 17 611719   35983               

Error: Within
           Df Sum Sq Mean Sq F value Pr(>F)
Beech       1   6244    6244  2.4194 0.1221
Residuals 139 358724    2581   

I'm interested in the Age-effect. What is wrong with this model?
Additional I've tried to compute an lme with 

 model<-lme(Biomass~Age,random=~1|Age/Stand)

 anova(model)
            numDF denDF  F-value p-value
(Intercept)     1   140 61.17626  <.0001
Age             1     0  2.70482     NaN
Warning message:
NaNs produced in: pf(q, df1, df2, lower.tail, log.p) 

This can't be the right way, or? What is wrong?

thanks for your ideas.

Jörn Buse
Lueneburg, Germany

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