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# Re: st: Multistage sampling svyset

 From Steve Samuels To statalist@hsphsun2.harvard.edu Subject Re: st: Multistage sampling svyset Date Thu, 10 Jun 2010 15:18:11 -0400

```OK, I read your email in detail.  Let pcomm = (N hh in the stratum)/n
hh in the sample from the stratum)

_If_ the survey was done as you describe the -svyset- should go:

svyset houseid [pw=pwgt], strata(pi4) fpc(pcomm)

The proportion of people selected in the HH (the last stage)  affects
only the sampling weight.

Please verify how the HH were selected  Was there a list of HH from
which HH were sampled?   Or, was there an intermediate sample of areas
(such as blocks) drawn first, with HH sampled only in the selected
areas?

Steve

On Thu, Jun 10, 2010 at 3:04 PM, Steve Samuels <sjsamuels@gmail.com> wrote:
> James, what is "pi4"? What is the variable which identifies the
> community?  How did you compute the sampling weight "pwgt"?  (show an
> example, as well as code.)
>
> Steve
>
>
> On Thu, Jun 10, 2010 at 2:33 PM,  <James.Valcour@med.mun.ca> wrote:
>> I'm having a problem using the survey commands to analyzing a survey
>> that used a complex sampling design.
>>
>> Eleven communities were sampled (these were all the communities in the
>> study area).  Within each community households were randomly selected
>> from all available households.  Within each household one person was
>> randomly select from all members of the household that were eligible to
>> be in the survey (we had a list of everybody eligible in the house).
>>
>> This is the code I used to set the data:
>>
>> svyset houseid [pw=pwgt], strata(pi4) fpc(p_household) || _n,
>> fpc(p_person)
>>
>> where
>> houseid is an identifier for the house in the community; a mix of the
>> community id number and the house number
>> pi4 is an identified for the community (1-11)
>> p_household is the probability of selection of the household in the
>> community
>> p_person is the probability of selection of the person in the household
>>
>> The problem I'm getting is when I'm trying to estimate the proportion of
>> study with certain ailments.  I'm not getting confidence intervals
>> included in the estimates.  The message that is given is " Note: missing
>> standard errors because of stratum with single sampling unit."
>>
>> I've tried other ways of specify the svyset command and tried
>> simplifying to the point of just assuming that household were sampled
>> but I get the same error.  (for the record here's that command "svyset
>> _n [pw=pwgt], strata(pi4) fpc(p_household)")
>>
>> Any help would be appreciated,
>>
>> Thanks!
>> James Valcour
>>
>> --
>> Dr. James Valcour
>> Division of Community Health and Humanities
>> Faculty of Medicine
>> The Health Sciences Centre
>> Memorial University of Newfoundland
>> A1B 3V6
>> Tel:  709-777-2237
>> Fax: 709-777-7382
>> Email: james.valcour@med.mun.ca
>>
>>
>>
>> *
>> *   For searches and help try:
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>>
>
>
>
> --
> Steven Samuels
> sjsamuels@gmail.com
> 18 Cantine's Island
> Saugerties NY 12477
> USA
> Voice: 845-246-0774
> Fax:    206-202-4783
>

--
Steven Samuels
sjsamuels@gmail.com
18 Cantine's Island
Saugerties NY 12477
USA
Voice: 845-246-0774
Fax:    206-202-4783

*
*   For searches and help try:
*   http://www.stata.com/help.cgi?search
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/
```