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Lack of Variation in Slopes

4 messages · AvianResearchDivision, Ben Bolker

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AvianResearchDivision <segerfan83 at ...> writes:
I strongly suspect that the problem is that the estimated random
effects variation in the slope of A with respect to B across Males is
zero.  This happens with some regularity, especially for relatively
small data sets, or complex models.  You're estimating a lot of
variation in B in the fixed effects (interaction with the 11-level factor 
C), so it doesn't shock me that under some circumstances you get
a zero estimate for sigma^2_(B|Male).

You can easily test this explanation by looking at the summary(), or VarCorr(),
to see if that variance component is zero (or very small).

 Ben Bolker
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AvianResearchDivision <segerfan83 at ...> writes:
[snip]
I don't think it will hurt.