"when the first level denotes failure and all others success" Yes, I saw this sentence in the glm help file, but I hadn't understood it this way... Anyway I checked this with a few examples and this is exactly what it does. Thanks a lot for your help !!!
I can go back now to the polr function and try to understand why my results were better with glm. By the way, does anyone know how I can solve the likelyhood maximization problem : "attempt to find suitable starting values failed" obtained with polr : require(MASS) data(iris) polr(Species~Sepal.Length+Sepal.Width+Petal.Length+Petal.Width,iris) (I know this has to be a nominal model but I do as levels were ordered for the example). I tried to solve this by setting the "start" option to a null or a random vector by it doesn't garantee to find "a good" solution at the end. Thanks a lot ! -- View this message in context: http://r.789695.n4.nabble.com/glm-prediction-of-a-factor-with-several-levels-tp2300793p2302927.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
