[R-sig-ME] Justification to exclude random effect

[Reuben Smit]

Hello,

The results of my mixed model show the single random effect variance and
standard deviation equal to zero. A statistician reviewed my results and
suggested the random effect is not explaining any additional variance apart
from the fixed effects. I'm asking the list to support or refute this claim
based on the aforementioned variance and standard deviation estimate. If
indeed the random effect is not contributing to the model, is it justified
to exclude the random effect and may I use a more simple generalized linear
model with fixed effects only?

Also, the random effect is the effect of Site from a random nested study
design. My conjecture is that a longitudinal/spatial fixed effect is
accounting for relatedness between sample points located in the same Site
(block).

Thanks in advance,
Reuben

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