Re: [R] Is it possible to use glm() with 30 observations?

2005-07-02 Thread Spencer Graves
I agree with Ted: "in model-fitting terms, it is a resounding success!" With any data set having at least one point with a binomial yield of 0 or 100%, you can get this phenomenon by adding series of random numbers sequentially to a model. Eventually, you will add enough variables t

Re: [R] Is it possible to use glm() with 30 observations?

2005-07-02 Thread Ted Harding
On 02-Jul-05 Kerry Bush wrote: > I have a very simple problem. When using glm to fit > binary logistic regression model, sometimes I receive > the following warning: > > Warning messages: > 1: fitted probabilities numerically 0 or 1 occurred > in: glm.fit(x = X, y = Y, weights = weights, start = >

Re: [R] Is it possible to use glm() with 30 observations?

2005-07-02 Thread David Firth
On 2 Jul 2005, at 06:01, Spencer Graves wrote: > The issue is not 30 observations but whether it is possible to > perfectly separate the two possible outcomes. Consider the following: > > tst.glm <- data.frame(x=1:3, y=c(0, 1, 0)) > glm(y~x, family=binomial, data=tst.glm) > > tst2.glm <-

Re: [R] Is it possible to use glm() with 30 observations?

2005-07-01 Thread Spencer Graves
The issue is not 30 observations but whether it is possible to perfectly separate the two possible outcomes. Consider the following: tst.glm <- data.frame(x=1:3, y=c(0, 1, 0)) glm(y~x, family=binomial, data=tst.glm) tst2.glm <- data.frame(x=1:1000, y=rep(0:1, eac