R help - Jul 2011 - cv.glm and "longer object length is not a multiple of shorter object length" error

Hi,

I've done some searching where others have had trouble with this error (or
"warning" actually), but I'm unable to solve my problem.  I have a
data
sheet with 13 columns and 36 rows.  Each column has exactly the same number
of rows.  I've created glms and now want to do cross-validation on 2 of
them.  Please be gentle-- I'm new to R (and statistics, too, for that
matter).  Any help is greatly appreciated.  Here's my code:

/library(boot)
n<-length(total_species)
cv13.err<- cv.glm(nests,glm13)
cv13.err.5<- cv.glm(nests,glm13,K=5)
cv18.err<- cv.glm(nests,glm18)
cv18.err.5<- cv.glm(nests,glm18,K=5)/


I get errors starting with the glm18 part.  glm13 is
*total_species~RH+elev+RH*elev* and glm18 is *total_species~per_cover+RH*

Does it have something to do with the two glms having different numbers of
parameters?  I'm not sure why it seems okay with what I've done for
glm13,
but not glm18.  Thanks again for any help.

*Warning messages:
1: In y - yhat :
  longer object length is not a multiple of shorter object length*

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On 2011-07-21 17:29, askantik wrote:
> Hi,
>
> I've done some searching where others have had trouble with this error
(or
> "warning" actually), but I'm unable to solve my problem.  I
have a data
> sheet with 13 columns and 36 rows.  Each column has exactly the same number
> of rows.  I've created glms and now want to do cross-validation on 2 of
> them.  Please be gentle-- I'm new to R (and statistics, too, for that
> matter).  Any help is greatly appreciated.  Here's my code:
>
> /library(boot)
> n<-length(total_species)
> cv13.err<- cv.glm(nests,glm13)
> cv13.err.5<- cv.glm(nests,glm13,K=5)
> cv18.err<- cv.glm(nests,glm18)
> cv18.err.5<- cv.glm(nests,glm18,K=5)/
>
>
> I get errors starting with the glm18 part.  glm13 is
> *total_species~RH+elev+RH*elev* and glm18 is *total_species~per_cover+RH*
>
> Does it have something to do with the two glms having different numbers of
> parameters?  I'm not sure why it seems okay with what I've done for
glm13,
> but not glm18.  Thanks again for any help.
>
> *Warning messages:
> 1: In y - yhat :
>    longer object length is not a multiple of shorter object length*
My guess is that per_cover contains at least one missing value.
You could try

  cv.glm(na.omit(nests), glm18)

I tried glm(..., na.action = na.exclude) but cv.glm() appears not (yet)
to be coded to handle padding of missing values.

Peter Ehlers
>
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> View this message in context:
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> Sent from the R help mailing list archive at Nabble.com.
>
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