Hello, On Thu, Mar 7, 2013 at 2:20 PM, Sarah Goslee <sarah.gos...@gmail.com> wrote: > Hi, > >> I'm not sure how one would combine SEM / graphical models with compositional >> dissimilarity as a response. You might be able to fit a series of models in >> adonis() or capscale(), comparing just direct factors to direct + >> intermediate, etc.. I don't have any good ideas on how you might test more >> complex causal structures. >
Tom: thanks for chiming in. If I understand you correctly, your idea is similar to my colleague's first thought: he was asking about a sort of nested ANOVA/model approach (he didn't call it that, but that was what he was getting at). > There's a fair bit of literature on Mantel-based path analysis, and > other similar dissimilarity-based approaches. SEM can be used with > composition as well, although not (I think) with the intermediate step > of calculating dissimilarities. > > Besides journal articles employing those techniques, I like both of these: > > J. B. Grace, Structural Equation Modeling and Natural Systems, > Cambridge University Press, Cambridge, UK, 2006. > > B. Shipley, Cause and Correlation in Biology: A User’s Guide to Path > Analysis, Structural Equations and Causal Inference, Cambridge > University Press, Cambridge, UK, 2000. > Sarah: thank you again! I will definitely check these out. >> Given that you are dealing with diatoms across space (with environmental >> measurements) and down time (in cores, often without environmental >> measures), there may be an alternate approach possible based on calibration >> approaches to inferred environments (e.g., WACAL) or modern analogs. I >> would look at packages bio.infer, paltran, fossil, and analogue, and search >> to see if anyone has pushed them in the direction you want to go. >> Tom: many, many thanks. I have not used any of those packages before. I will investigate every single one. Jay _______________________________________________ R-sig-ecology mailing list R-sig-ecology@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-ecology