bigglm binomial negative fitted value

On Fri, Jun 1, 2012 at 1:17 AM, Yue Guan <pipehappy at gmail.com> wrote:

Hi, there

Since glm cannot handle factors very well. I try to use bigglm like this:

logit_model <- bigglm(responser~var1+var2+var3, data, chunksize=1000,
family=binomial(), weights=~trial, sandwich=FALSE)

fitted <- predict(logit_model, data)

only var2 is factor, var1 and var3 are numeric.

I expect fitted should be a vector of value falls in (0,1)

However, I get something like this:
str(fitted)
?num [1:260617, 1] -0.0564 -0.0564 -0.1817 -0.1842 -0.1852 ...
?- attr(*, "dimnames")=List of 2
?..$ : chr [1:260617] "1" "2" "3" "4" ...
?..$ : NULL

As the help says, the default is predictions of the linear predictor.
To get predictions of the probability, use type="response"

? -thomas

--
Thomas Lumley
Professor of Biostatistics
University of Auckland