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Problem with ordered probit model in MASS
2 messages · justin bem, Brian Ripley
On Wed, 24 Jan 2007, justin bem wrote:
(Again: this is a duplicate post.)
Dear all, I got this message, while using the polr function in MASS
EQ<-as.formula("dep~fpta+tcdv+cdta+cmta+prcd+patc+lactifs+excta")
Estim<-polr(EQ,don, subset=(cote!=0),method="probit",na.action=na.omit)
Error in polr(EQ, don, subset = (cote != 0), method = "probit", na.action = na.omit) :
attempt for find suitable starting values failed
In addition: Warning messages:
1: algorithm did not converge in: glm.fit(X, y1, wt, family = binomial("probit"), offset = offset)
2: fitted probabilities numerically 0 or 1 occurred in: glm.fit(X, y1, wt, family = binomial("probit"), offset = offset)
how can I initialise starting values ?
What do you think the 'start' argument to polr() is for? If you are asking how you find suitable values, I cannot help you as I know nothing about your problem, and failing to find starting values usually means that the model is very far from appropriate.
Justin BEM El?ve Ing?nieur Statisticien Economiste BP 294 Yaound?. T?l (00237)9597295.
Brian D. Ripley, ripley at stats.ox.ac.uk Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595