Hi, mantel statistics has repeatedly been criticized. I wonder if there is an (approved) alternative for my problem: I aim to test whether one parameter (productivity, P) affects turnover (t) among ecological communities in time (T) or space (S). (ÎT and ÎS will be used as a co-variables). To avoid confusion - I do NOT aim to test whether P affects composition as such (which could be tested by an ordination method), but whether the degree of similarity among samples scales with P. My approach so far was to calculate a dissimilarity matrix from my community data, distance matrices for the relevant environmental data (ÎT, ÎS, ÎP) and a mean (P) matrix, giving the mean(P) for each pair of observations. The I performed mantel tests whether t correlates with mean(P), taking other variables into account (partialing out). However, mantel and especially partialing out are often criticized (e.g. see documentation in vegan). any views? thanks! Robert
Robert Ptacnik, PhD ICBM, Univ. of Oldenburg Schleusenstrasse 1, DE-26382 Wilhelmshaven http://www.icbm.de/planktologie/en/ ptac...@icbm.de FON +49 4421 944-205 FAX +49 4421 944-299 mobile: +49 173 6470130 [[alternative HTML version deleted]]
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