[R] User error in calling predict/model.frame

[David Winsemius]

On Jan 29, 2011, at 12:12 PM, Russell Pierce wrote:

> Just in case someone else stumbles onto this thread and is facing a
> similar issue:  The quick solution for me turned out to be using Glm
> and Predict in the rms package.  Thanks go to Joshua and Ista for
> helping me out with this issue.  Double thanks go to Joshua for
> suggesting I take a closer look at the rms package.
>
> library(rms)
> dat <- data.frame(xxA = rnorm(20,10), xxB = rnorm(20,20))
> dat$out <- with(dat,xxA+xxB+xxA*xxB+rnorm(20,20))
> rms.res <- Glm(out ~ scale(xxA)*scale(xxB),data=dat)
> newdata <- as.data.frame(Predict(rms.res,xxA=c(-1,0,1),xxB=c(-1,0,1)) 
> [,1:3])

Puzzled that you would see a particular need for the rms functions  
(not that I have anything against the rmes package, but it doesn't  
seem to be needed here.)

This seems to work without error:

rms.res <- glm(out ~ scale(xxA)*scale(xxB), data=dat)
newdata <- predict(rms.res,  
newdata=data.frame(xxA=c(-1,0,1),xxB=c(-1,0,1)))

-- 
David Winsemius, MD
West Hartford, CT