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2008 Aug 22
1
lme questions re: repeated measures & covariance structure
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 f...