Dear all,
I'm working with a model to estimate components of variance by using the
lme() function.
The model is as the following:
model=lme(fixed=X~1+as.factor(station),data=myData,na.action=na.exclude,rand
om=~N+1|spliceOrHoming)
Where X is the response measured variable, station is treated as fixed
effects factor, N is a continuous variable, and spliceOrHoming is a
(ordered) factor.
The idea is that the response variable (X) varies almost linearly with N (in
a decreasing fashion) , but the slope and intercept of this variation change
with the levels of spliceOrHoming random factor.
Now, the REML estimated standard deviation components are:
StdDev Corr
(Intercept) 5.274544e-01 (Intr)
N 7.912717e-05 -0.58
Residual 1.508647e-01
My questions are:
. Is the model correctly specified?
. If yes, how should I read the standard deviation estimate for N
(7.912717e-05)? Is this the standard deviation for a unitary variation of
N? Or is it the standard deviation due to the "global" contribution of the N
independent variable? (note that I have a strong feeling that N contributes
a lot to the final variance; so, the value that I obtain here seems "too
small" for my beliefs)
. Is there any methods/functions to obtain the variance components
for the station factor too? (please, give me some references, at least.)
Thank you a lot in advance for every suggestions you'll give me.
Enrico
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