predict.lm(...,type="terms") question

On Aug 30, 2012, at 4:35 PM,  David Windemius wrote:

David said my newdata data frame 'new' must have a column named  
'area'.
It did. Nonetheless predict.lm throws an error with type = "terms"  
and
newdata = new. I see nothing in the predict.lm  documentation that
bars this usage. Is there a bug?

After correcting the error in your definition of the 'area' vector I
get no error from predict.lm().

David.

What error did you correct?

This was the code you offered:

#Ludbrook's data set S1 (except renaming
#his 'x' as 'concn' and his 'y' as 'area')
S1 <- data.frame(
     area = c(2.4,2.6,6.0,6.5,8.9,),
     concn = c(1.1,4,5,8.5,8.5))

There's an extra comma in the "area" vector.

The newdata data frames in my examples have been pretty simple, and  
have
defined the 'area' vector simply, for instance,
new <- data.frame(area = c(8172, 10220, 11570, 24150))
new
#        area
#    1  8172
#    2 10220
#    3 11570
#    4 24150

Is something wrong with this?

I don't really know  ....  this appears to be a different problem than  
you posed earlier. If you would learn to post with context, we might  
not be in the position of trying to read your mind.

 Were you able to make predict.lm work with newdata = new and type =  
"terms"?

Yes. I have no trouble doing so.

 >  x <- rnorm(15); x2=rnorm(15)
 >  y <- x + x2 +rnorm(15)
 >  fit <- lm(y ~ x+x2)
 >  new <- data.frame(x2 = seq(-3.5, 3.5, 0.5)  )
 >  predict(fit, newdata=new,type="terms", terms="x2")
            x2
1  -4.9230035
2  -4.1850588
3  -3.4471141
4  -2.7091694
5  -1.9712248
6  -1.2332801
7  -0.4953354
8   0.2426093
9   0.9805539
10  1.7184986
11  2.4564433
12  3.1943880
13  3.9323326
14  4.6702773
15  5.4082220
attr(,"constant")
[1] 0.4501911

-John

Sent from the (NOT) R help mailing list  (and NOT) archive at  
Nabble.com.

Hmmm ... Nabble ... definitely part of the problem.

David Winsemius, MD
Alameda, CA, USA