[R] Survey Package with Binary Data (no Standard Errors reported)
Thomas Lumley
tlumley at u.washington.edu
Mon Apr 6 11:56:36 CEST 2009
On Fri, 3 Apr 2009, Paul Jones wrote:
> Hi,
>
> I'm trying to get standard errors for some of the variables in my data frame.
> One of the questions on my survey is whether faculty coordinate across
> curriculum to include Arts Education as subject matter. All the responses are
> coded in zeros and ones obviously. For some of the other variables I have a 2
> for those that responded with "Don't Know".
>
> I'm getting NA for mean and standard deviations from svymean. Am I doing
> something wrong of can the survey package not handle this type of data?
Are you sure you don't have any NA values in the data? If you do, the
na.rm=TRUE option to svymean() will fix your problem. If you don't,
something mysterious is happening. You could try svytable(~Curriculum,
survey), which will give a tabulation and might show up what is strange
about your data.
As a separate issue, you might want to look at svyciprop() if some of your
proportions are close to 0 or 1, to get better confidence intervals.
> Here's my code.
Nothing obviously wrong with it.
-thomas
>> survey <- svydesign(id=~1, data=General, strata=~Grade.Level)
> Warning message:
> In svydesign.default(id = ~1, data = General, strata = ~Grade.Level) :
> No weights or probabilities supplied, assuming equal probability
>
>> summary(survey)
> Stratified Independent Sampling design (with replacement)
> svydesign(id = ~1, data = General, strata = ~Grade.Level)
> Probabilities:
> Min. 1st Qu. Median Mean 3rd Qu. Max.
> 1 1 1 1 1 1
> Stratum Sizes:
> Elementary High Middle
> obs 312 236 156
> design.PSU 312 236 156
> actual.PSU 312 236 156
> Data variables:
> [1] "Grade.Level" "Curriculum" [3]
> "Field.Trips" "Residencies" [5] "PTA.Support"
> "Community.Open.Performances"
> [7] "Visual.Arts.Attendance" "Literary.Arts.Attendance" [9]
> "Arts.Organization.Membership" "Arts.Essential"
> > svymean(~Curriculum, survey)
> mean SE
> Curriculum NA NA
>
> ???
>
> PJ
>
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> and provide commented, minimal, self-contained, reproducible code.
>
Thomas Lumley Assoc. Professor, Biostatistics
tlumley at u.washington.edu University of Washington, Seattle
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