Hello,

We are attempting to use nlme to fit a linear mixed model to explain bird
abundance as a function of habitat:


lme(abundance~habitat-1,data=data,method="ML",random=~1|sampleunit)

The data consist of repeated counts of birds in sample units across multiple
years, and we have two questions:

1) Is it necessary (and, if so, how) to specify the repeated measure
(years)? As written, the above code does not.

2) How can we specify a Toeplitz heterogeneous covariance structure for this
model? We have searched the help file for lme, and the R-help archives, but
cannot find any pertinent information. If that's not possible, can we adapt
an existing covariance structure, and if so how?

Thanks, Mark

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