[R] Another Mix Model Question

[Alfonso M Sanchez-Lafuente]

Hi again,

thank you for your previous answers. Just another question, though ...

I get the following variance components after fitting a mixed model.


Groups   Name              Variance Std.Dev. Corr
PlantID  TreatmCtrl        0.51784  0.71961
          TreatmNoAccess    4.77469  2.18511  -0.063
          TreatmNoKeel      4.22726  2.05603   0.513  0.751
          TreatmNoSpur      0.45918  0.67763   0.158  0.303  0.319
          TreatmNoStand     3.45357  1.85838  -0.736 -0.070 -0.435 0.495
PlantID  PollClassApis     1.12364  1.06002
          PollClassBombAnth 0.42769  0.65398  -0.759
Residual                   3.09669  1.75974

My question is: if n random effects are included in a model, how can I 
test the hypothesis that the variance of such effects is 0 ?

Some sort of COVTEST option in Proc MIXED in SAS (sorry, SAS is still 
more familar to me than R).

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Alfonso M. Sanchez-Lafuente
Departamento de Biologia Vegetal y Ecologia
Facultad de Biologia
Universidad de Sevilla
Avd. Reina Mercedes 9
E-41012, Sevilla, Spain
email: alfonso at slafuente.net / slafuente at us.es