R help - Mar 2011 - sampling design runs with no errors but returns empty data set

Dear colleagues,
I'm working with the 2008 Canada Election Studies
(http://www.queensu.ca/cora/_files/_CES/CES2008.sav.zip), trying to construct a
weighted national sample using the survey package.
Three weights are included in the national survey (a household weight,  a
provincial weight and a national weight which is a product of the first two).
In the following code I removed variables with missing national weights and
tried to construct the sample from advice I've gleaned from the
documentation for the survey package and other help requests.
There are no errors, but the data frame (weight_test) contains no 
What am I missing?  
Yours, Simon Kiss
P.S. The code is only reproducible if the data set is downloadable.  I'm nt
sure

ces<-read.spss(file.choose(), to.data.frame=TRUE, use.value.labels=FALSE)
missing_data<-subset(ces1, !is.na(ces08_NATWGT))
weight_test<-svydesign(id=~0, weights=~ces08_NATWGT, data=missing_data)

Note: this is some reproducible code that creates a data set that is a very
stripped down version of what I'm working with, but with this, the
surveydesign function appears to work properly.

mydat<-data.frame(ces08_HHWGT=runif(3000, 0.5, 5), ces08_PROVWGT=runif(3000,
0.6, 1.2), party=sample(c("NDP", "BQ", "Lib",
"Con"), 3000, replace=TRUE), age=sample(seq(18, 72,1), 3000,
replace=TRUE), income=sample(seq(21,121,1), 3000, replace=TRUE))
mydat$ces08_NATWGT<-mydat$ces08_HHWGT*mydat$ces08_PROVWGT
weight_test<-svydesign(id=~1, weights=~ces08_NATWGT, data=mydat)



*********************************
Simon J. Kiss, PhD
Assistant Professor, Wilfrid Laurier University
73 George Street
Brantford, Ontario, Canada
N3T 2C9
Cell: +1 519 761 7606

On Thu, Mar 31, 2011 at 4:01 AM, Simon Kiss <sjkiss at gmail.com>
wrote:
> Dear colleagues,
> I'm working with the 2008 Canada Election Studies
(http://www.queensu.ca/cora/_files/_CES/CES2008.sav.zip), trying to construct a
weighted national sample using the survey package.
> Three weights are included in the national survey (a household weight, ?a
provincial weight and a national weight which is a product of the first two).
> In the following code I removed variables with missing national weights and
tried to construct the sample from advice I've gleaned from the
documentation for the survey package and other help requests.
> There are no errors, but the data frame (weight_test) contains no
> What am I missing?
> Yours, Simon Kiss
> P.S. The code is only reproducible if the data set is downloadable.
?I'm nt sure
>
> ces<-read.spss(file.choose(), to.data.frame=TRUE,
use.value.labels=FALSE)
> missing_data<-subset(ces1, !is.na(ces08_NATWGT))
> weight_test<-svydesign(id=~0, weights=~ces08_NATWGT, data=missing_data)
>
The code isn't reproducible even with the data.  The code refers to a
data frame ces1, which isn't defined, and to a variable ces08_NATWGT
that isn't in the data set.

However, a bit of Googling suggests that the variable CES08_NA is
probably the one you mean, giving the following code

library(survey)
library(foreign)
ces<-read.spss("CES2008.sav", to.data.frame=TRUE,
use.value.labels=FALSE)

missing_data<-subset(ces, !is.na(CES08_NA))
weight_test<-svydesign(id=~0, weights=~CES08_NA, data=missing_data)

which seems to produce a perfectly reasonable survey design object.
> weight_test
Independent Sampling design (with replacement)
svydesign(id = ~0, weights = ~CES08_NA, data =
missing_data)
> dim(weight_test)
[1] 3257  531
> svymean(~factor(GENDER),weight_test)
                   mean   SE
factor(GENDER)1 0.47362 0.01
factor(GENDER)5 0.52638 0.01


Since you don't say how you concluded the object contained no, I don't
know what you were seeing.  Note that weight_test is not supposed to
be a data frame. It's a survey design object.

   -thomas

-- 
Thomas Lumley
Professor of Biostatistics
University of Auckland