More on problem with polr
(those concerned about finding out who I am will find clues carefully hidden towards the end of this message) Briefly, I'm using polr (from the MASS library) to re-run an analysis I did about 18 months ago, with a previous version of R (I'm now using 1.5.0, I think I was using 1.2.x or 1.1.x before). It ran fine before, but now I'm getting an error. David Duffy suggested I post a minimum data set to demonstrate the problem, so here is one which shows the error - not having the old versoin of R, I can't check whether it would work with that:
Habitat <- factor(c(1, 1, 1, 1, 1, 2, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1)) Wings <- factor(c(3, 2, 2, 3, 2, 2, 2, 3, 2, 2, 3, 3, 3, 3, 3, 2, 3, 2)) Ext <- factor(c(1, 1, 2, 5, 2, 2, 2, 2, 2, 1, 7, 7, 1, 2, 3, 1, 4, 2), ordered=TRUE) library(MASS) Model1 <- polr(Ext ~ Habitat + Wings) Model2 <- polr(Ext ~ Habitat * Wings)
Error in optim(start, fmin, gmin, method = "BFGS", hessian = Hess) :
non-finite value supplied by optim
The full data set is much bigger (over 380 observations), but I can provide it if someone wants to look at it in more detail. The full data set does have "holes" in it (i.e. combinations of levels with no observations), but similar data sets with the same sorts of holes run fine. Thanks in advance for any help! Bob
Bob O'Hara Metapopulation Research Group Division of Population Biology Department of Ecology and Systematics PO Box 65 (Viikinkaari 1) FIN-00014 University of Helsinki Finland tel: +358 9 191 57913 mobile: +358 50 599 0540 fax: +358 9 191 57694 email: bob.ohara at helsinki.fi <http://www.helsinki.fi/science/metapop/> is not where it's at It is being said of a certain poet, that though he tortures the English language, he has still never yet succeeded in forcing it to reveal his meaning - Beachcomber -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._