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Showing posts from May, 2009

Principal coordinate analysis and the quest for a solution to a non-existent problem

I had an interesting experience yesterday - spent a good few hours on a silly problem. You don't need to know the technicality of the analyses at all, but I'm sure you'll appreciate the humour in this. I am frequently running principal coordinate (PCo) analyses recently. This is because I am using an interesting application of multiple regressions and PCoA on phylogeny vs phenotypic variables called the phylogenetic eigenvector regression (PVR; Diniz-Filho et al., 1998; Desdevises et al., 2003). In short, you take a phylogenetic tree of a given group of animals (or plants, or whatever your favourite group of organism), reduce the complex topology into manageable columns of numbers (by PCoA), and test these columns with some phenotypic/ecological variable of your choice for any correlations using multiple regression. Sounds pretty easy, and it is, in practice at least. You can code R to do this very efficiently, if you know the R language already. Anyway, yesterday, I