The correlation structure from the present model is derived from the Brownian motion model by multiplying the off-diagonal elements (i.e., the covariances) by \(\lambda\). The variances are thus the same than for a Brownian motion model.
corPagel(value, phy, form = ~1, fixed = FALSE)
# S3 method for corPagel
corMatrix(object, covariate = getCovariate(object),
corr = TRUE, ...)
# S3 method for corPagel
coef(object, unconstrained = TRUE, …)the (initial) value of the parameter \(\lambda\).
an object of class "phylo".
(ignored).
a logical specifying whether gls should
estimate \(\lambda\) (the default) or keep it fixed.
an (initialized) object of class "corPagel".
(ignored).
a logical value specifying whether to return the correlation matrix (the default) or the variance-covariance matrix.
a logical value. If TRUE (the default),
the coefficients are returned in unconstrained form (the same used
in the optimization algorithm). If FALSE the coefficients are
returned in ``natural'', possibly constrained, form.
further arguments passed to or from other methods.
an object of class "corPagel", the coefficients from an object
of this class, or the correlation matrix of an initialized object of
this class. In most situations, only corPagel will be called
by the user.
Freckleton, R. P., Harvey, P. H. and M. Pagel, M. (2002) Phylogenetic analysis and comparative data: a test and review of evidence. American Naturalist, 160, 712--726.
Pagel, M. (1999) Inferring the historical patterns of biological evolution. Nature, 401,877--884.