On Jan 16, 2010, at 1:34 PM, Maurice Charbit wrote:
Hi,
See below I reply your message for <https://stat.ethz.ch/pipermail/r-help/2008-April/160966.html
>[R] predict.glm & newdata posted on Fri Apr 4 21:02:24 CEST 2008
You say it ##works fine but it does not: if you look at the length
of yhat2, you will find 100 and not 200 as expected. In fact
predict(reg1, data=x2) gives the same results as predict(reg1).
So I am still looking for a solution of this problem.
You are replying to a posting that is almost two years old. The
posting back then was incomplete in that y1 was never defined. Why not
post a more complete and updated question?
--
David.
best regards
Maurice
===========
Hi,
could it be the "newdata" argument? When I run predict with the
newdata
argument, I get an error message - a different one though. The
second reason
might be that your dataset is named df, which is defined as a
function an
may produce problems. Try renaming the dataset.
yhat=predict(reg1,newdata=x2)
x1=seq(1:100)
r.norm1=rnorm(100,0,20)
x1=r.norm1+x1
x2=x1*2
r.norm2=rnorm(200,0,20)
x2=r.norm2+x2
reg1=glm(y1~x1,binomial)
yhat=predict(reg1) ##prediction works fine
yhat=predict(reg1,newdata=x2) ##gives error message because of
"newdata"
Error in eval(predvars, data, env) :
numeric 'envir' arg not of length one
yhat=predict(reg1,data=x2) ##works fine
##using offset
ofst=rep(0.5,100)
reg1=glm(y1~x1,binomial,offset=ofst)
yhat=predict(reg1)
yhat1=predict(reg1,newdata=x2) ##gives error message
yhat2=predict(reg1,data=x2) ##works fine
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