Dear all,
I am working with flower allometry and want to use PGLS to analyse how the male
and female biomass of the flower scale with total flower biomass.
So simple linear regressions, but log-trasformed.
my model is:
mod.male <- pgls(male~total, data=flower.data,lambda="ML")
Besides calculatin
Dear Jorge,
For simplicity, I'd start with these two papers, both available on my webpage:
Purvis, A., and T. Garland, Jr. 1993. Polytomies in comparative analyses of
continuous characters. Systematic Biology 42:569–575.
Theodore Garland, Jr., Paul H. Harvey, and Anthony R. Ives. 1992. Procedur
Dear All,
I'm working on some comparative analyses involving up to 312 populations of
birds representing 112 species, one dependent variable (sometimes count data,
e.g. species richness), various continuous independent variables (e.g.
latitude, body mass), and a categorical variable (habitat:
Thank you guys for you helpful advice!
The probelm in my model is that it estimates lambda to be 1, however, my gut feeling would say this is rather unlikely. The model where lambda equals 1 looses significance completely, however, with lambda fixed at 0.85, it is highly significant. So what d
Hi Sereina.
Why lambda=0.5? Normally investigators tend to compare a model where
lambda is estimated to one in which it is fixed at 1 which corresponds
to Brownian evolution; or 0 which corresponds to no phylogenetic
correlation in the residual error of the model.
We can compare two fitted m
Dear all,
I have a question conserning the pgls regression in package caper. The function allows to estimate or fix three branch length transformations. I wanna figure out which transformation gives me the best model fit by comparing for example a model with lambda estimated (lambda="ML") to a
