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About two years ago there was a thread about this which suggested that at that time nobody had these coefficients ready to go. (a) has anyone in the meanwhile programmed them? (b) I think I can see how to do the tetrachoric one with mvtnorm on similar lines to an example on the help page so will try that if nobody else already has (c) looking at the polychoric one makes me realise yet again

Dear all i could not estimate the optima value or range value in unimodal plot in glm please help me out thanking you regard madan _________________________________________________________________ Hotmail® has a new way to see what's up with your friends. orial_WhatsNew1_052009 [[alternative HTML version deleted]]

....pacR ~ SumSST + I(SumSST^2), data = ImbrieKipp/100,           family = binomial) ## plot it pdat <- data.frame(SumSST= seq(min(SumSST), max(SumSST), length = 100)) p2 <- predict(mod, pdat, type = "response") lines(p2 ~ SumSST, data = pdat, col = "blue", lwd = 3) ## model ceofficients c.mod <- coef(mod) ## optima -c.mod[2]/(2 * c.mod[3]) ## tolerance sqrt(-(1/(2 * c.mod[3]))) ## height == abundance at optimum exp(c.mod[1] - (c.mod[2]^2/(4 * c.mod[3]))) HTH G -- %~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~% Dr. Gavin Simpson            [t] +44 (0...