Hi all. I am examining otolith morphology using elliptical Fourier analysis and shape indices. I am using the MASS package in R to run a quadratic discriminant function analysis and I have gotten myself in a bit of a tizzy!
I am a confused about how to present the results from the QDF. Most people state the Jack-knife classifications in a table but I have seen one paper that has plotted the centroid and 95% confidence ellipse (see link) http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0034481 1. I don't understand what this plot represents. Is it the posterior probabilities and if so is it correct to represent the data like this? 2. I have trawled through google and came across a link with code for the iris dataset. The author also plots the centroid and 95% confidence ellipse and this is of the posterior probabilities (but uses linear DA). 3. I have ran a linear DA on my data just to get to grips with discriminant function in R. Ordination of the two discriminant axes (I have three groups) versus plotting the posterior probabilities and confidence ellipses produce very different results...... as expected I guess. Are both methods correct but just different ways of visualizing the data? And how does this apply in the context of QDF Any insights would be greatly appreciated. Thanks, Eimear *Eimear Marie Ceileadh Egan* *PhD Candidate* Marine Ecology Research Group. University of Canterbury, School of Biological Sciences, Private Bag 4800, Christchurch 8140, New Zealand *Telephone* +64 3 364 2987 -- MORPHMET may be accessed via its webpage at http://www.morphometrics.org To unsubscribe from this group and stop receiving emails from it, send an email to morphmet+unsubscr...@morphometrics.org.
