From: Petr Pikal <petr.pikal_at_precheza.cz>

Date: Fri 16 Jul 2004 - 21:39:29 EST

R-help@stat.math.ethz.ch mailing list

https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Fri Jul 16 21:47:30 2004

Date: Fri 16 Jul 2004 - 21:39:29 EST

Hi Ann

As I read your code mode closely, I suspect that there could be another variables x1 and x2 somewhere in your search path which led to the error.

With fresh R session without any data this works as expected

dold<-data.frame(x1=rnorm(10),x2=5*rnorm(10))
y<-1:10

predict(lm(y~x1+x2,dold),dn,se.fit=T)

Cheers

Petr

On 16 Jul 2004 at 13:19, Petr Pikal wrote:

*> Hi
**>
*

> On 16 Jul 2004 at 12:38, Anne wrote:

*>
**> > hello to all!
**> >
**> > I have a small problem wit predict() for lm
**> >
**> > Let's say I have predictors x1 and x2, response y
**> >
**> > I want to predict for a new ds say
**> > dn<-data.frame(x1=
**> > seq(min(x1),max(x1),length=10),x2=rep(median(x2),10))
**> >
**> > predict(lm(y~x1+x2),dn,se.fit=T)
**> >
**> >
**> > Error message
**> > > Error: variables 'x1', 'x2' were specified differently from the
**> > > fit
**>
**> AFAIK predixt require to be fed by dataframe in which the
**> variables has the same names as was in lm() call. Either call lm()
**> with variables named "x1" and "x2" or build the dataframe "dn" with
**> names identical as are names in lm() call
**>
**> Cheers
**> Petr
**>
**>
**> >
**> > (I looked in the help and found the example
**> >
**> > x <- rnorm(15)
**> > y <- x + rnorm(15)
**> > new <- data.frame(x = seq(-3, 3, 0.5))
**> > predict(lm(y ~ x), new, se.fit = TRUE)
**> >
**> > where is the difference?)
**> >
**> >
**> > Anne
**> >
**> > ----------------------------------------------------
**> > Anne Piotet
**> > Tel: +41 79 359 83 32 (mobile)
**> > Email: anne.piotet@m-td.com
**> > ---------------------------------------------------
**> > M-TD Modelling and Technology Development
**> > PSE-C
**> > CH-1015 Lausanne
**> > Switzerland
**> > Tel: +41 21 693 83 98
**> > Fax: +41 21 646 41 33
**> > --------------------------------------------------
**> >
**> > [[alternative HTML version deleted]]
**> >
**> > ______________________________________________
**> > R-help@stat.math.ethz.ch mailing list
**> > https://www.stat.math.ethz.ch/mailman/listinfo/r-help
**> > PLEASE do read the posting guide!
**> > http://www.R-project.org/posting-guide.html
**>
**> Petr Pikal
**> petr.pikal@precheza.cz
**>
**> ______________________________________________
**> R-help@stat.math.ethz.ch mailing list
**> https://www.stat.math.ethz.ch/mailman/listinfo/r-help
**> PLEASE do read the posting guide!
**> http://www.R-project.org/posting-guide.html
*

Petr Pikal

petr.pikal@precheza.cz

R-help@stat.math.ethz.ch mailing list

https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Fri Jul 16 21:47:30 2004

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