Re: [R] Avoiding singular fits in rlm

2009-12-03 Thread Matt Crawford
Thanks, that was right (factor levels with no data). I forgot or didn't know that when data gets changed, the factor levels don't get changed as well. I'm sorry about missing parts of the Posting Guide. Matt Crawford On Wed, Dec 2, 2009 at 10:45 PM, Prof Brian Ripley wrote: > There is something

Re: [R] Avoiding singular fits in rlm

2009-12-03 Thread Peter Ehlers
Matt Crawford wrote: I keep coming back to this problem of singular fits in rlm (MASS library), but cannot figure out a good solution. I am fitting a linear model with a factor variable, like lm( Y ~ factorVar) and this works fine. lm knows to construct the contrast matrix the way I would expec

[R] Avoiding singular fits in rlm

2009-12-02 Thread Matt Crawford
I keep coming back to this problem of singular fits in rlm (MASS library), but cannot figure out a good solution. I am fitting a linear model with a factor variable, like lm( Y ~ factorVar) and this works fine. lm knows to construct the contrast matrix the way I would expect, which puts the first