Dichotomous variables
Hi Marco,
On Fri, Aug 5, 2011 at 11:53 AM, marco <marco.milella at aim.uzh.ch> wrote:
Hi everyone, Have sample of items for each one, a set of 20 dichotomous (absent-present) variables are expressed. I'm trying to understand how to explore the co-occurence of each variable. Read some papers concerning smallest space analysis, but it does not seems implemented in any R package (and my protamming skills are =0). Non metric MDS gives error messages, probably because of the dichotomous character of my variables. My aim is basically to obtain a 2D plot with cooccurence expressed as distance between plots (variables). Any advice to such issue?
I would think that NMDS with a dissimilarity metric appropriate for presence-absence data is a reasonable place to start. Since you don't give any details about your data, or the commands you used to run NMDS, or even the error messages you received, we can't help further. You did calculate a dissimilarity before trying to run NMDS, right? Having binary variables doesn't make a bit of difference. Sarah
Sarah Goslee http://www.functionaldiversity.org