[R-sig-ME] Question about nested design

ONKELINX, Thierry Thierry.ONKELINX at inbo.be
Mon Jul 6 12:13:57 CEST 2009

Dear all,

I have a rather theoretical question about nested random effects.
Suppose the design has three levels S(ample), R(eplicate) and M(arker).
M is crossed with both S and R. R is nested in S. M has about 40 levels,
S 206 levels and R 251 levels. The difference in the number of levels
between S and R is rather small because 171 samples have only one
replicate. 22 samples have two replicates and 13 samples have three
replicates. Does it makes sense to add the nested effect of R to the
model? So the random structure would look like (1|M) + (1|S) + (1|S:R).
Or should I better stick to a model without the replicates (1|M) +
Changing the design to get replicates for all samples is not an option
as that would be too expensive and too much work.

Best regards,


ir. Thierry Onkelinx
Instituut voor natuur- en bosonderzoek / Research Institute for Nature
and Forest
Cel biometrie, methodologie en kwaliteitszorg / Section biometrics,
methodology and quality assurance
Gaverstraat 4
9500 Geraardsbergen
tel. + 32 54/436 185
Thierry.Onkelinx at inbo.be

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