[R-sig-phylo] caper model comparison with different branch length transformations

2014-08-20 Thread Sereina Graber
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

Re: [R-sig-phylo] caper model comparison with different branch length transformations

2014-08-20 Thread Liam J. Revell
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

Re: [R-sig-phylo] caper model comparison with different branch length transformations

2014-08-20 Thread Sereina Graber
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