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2013 Jan 26
2
confidence / prediction ellipse
...w these parameters are calculated for a confidence ellipse. ibrary(car) a=c(12,12,4,5,63,63,23) b=c(13,15,7,10,73,83,43) v <- cov.trob(cbind(a, b)) shape <- v$cov center <- v$center radius <- sqrt(2 * qf(0.95, 2, length(a) - 1)) # radius <- sqrt(dfn * qf(level, dfn, dfd)) conf.elip = ellipse(center, shape, radius,draw = F) plot(conf.elip, type='l') points(a,b) My question is how I can calculate shape, center and radius to obtain a prediction ellipses rather than a confidence ellipse? Thanks in Advance Giuseppe -- Giuseppe Amatulli Web: www.spatial-ecology.net [[...