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Re: st: Number of Obs with svy , suppop()
From
Tim Scharks <[email protected]>
To
[email protected]
Subject
Re: st: Number of Obs with svy , suppop()
Date
Thu, 18 Mar 2010 21:33:46 -0700
Sorry all, I understand Phil's point--they are added to the total
population, not the subpopulation.
The bit I pasted below was unintentional, I thought that it might have
something to do with the missing data but no...then didn't delete it.
Sorry!
Cheers, Tim
On Thu, Mar 18, 2010 at 9:14 PM, Tim Scharks <[email protected]> wrote:
> That sounds reasonable, Phil, but why are the WOMEN with (missing) for
> race added to the sample when men==1 was specified?
>
> Thanks, Tim
>
> takes on values other than 0 and 1
> subpop() != 0 indicates subpopulation
> (running tabulate on estimation sample)
>
> Number of strata = 1 Number of obs = 4000
> Number of PSUs = 4000 Population size = 7880496.9
> Subpop. no. of obs = 4000
> Subpop. size = 7880496.9
> Design df = 3999
>
> ------------------------
> 1=white, |
> 2=black, |
> 3=other | count
> ----------+-------------
> White | 6,930,316.91
> Black | 754,879.69
> Other | 195,300.31
> |
> Total | 7,880,496.91
> ------------------------
> Key: count = weighted counts
>
> .
> end of do-file
>
>
>
>
> On Thu, Mar 18, 2010 at 5:04 PM, Phil Schumm <[email protected]> wrote:
>> On Mar 18, 2010, at 6:20 PM, Michael Mitchell wrote:
>>>
>>> Here is the tabulation of race and sex by race.
>>
>> <snip>
>>
>>> . tab sex race, missing
>>>
>>> 1=male, | 1=white, 2=black, 3=other
>>> 2=female | White Black Other . | Total
>>> -----------+--------------------------------------------+----------
>>> male | 1,676 193 35 34 | 1,938
>>> female | 1,824 238 34 37 | 2,133
>>> -----------+--------------------------------------------+----------
>>> Total | 3,500 431 69 71 | 4,071
>>
>> <snip>
>>
>>> But now I want to analyze just the sub-population of males (sex==1) and it
>>> shows that the number of obs is now 4037 (see below). How can the number of
>>> observations increase when adding a -subpop()- option? There are suddenly
>>> 37 extra observations. Note this corresponds to the number of females with a
>>> missing race.
>>>
>>> . svy , subpop(if sex==1): tab race, count format(%13.2fc)
>>> (running tabulate on estimation sample)
>>>
>>> Number of strata = 1 Number of obs =
>>> 4037
>>> Number of PSUs = 4037 Population size =
>>> 7932333.9
>>> Subpop. no. of obs =
>>> 1904
>>> Subpop. size =
>>> 3780355.3
>>> Design df =
>>> 4036
>>
>>
>> This is as it should be, since information about race is not required on
>> those observations outside of the subpopulation. Remember, observations
>> outside the subpopulation are relevant only insofar as they reflect the
>> variability in the proportion(s) of sampled PSUs with at least one
>> observation in the subpopulation.
>>
>> In fact, at one point Stata did not behave properly in this regard; this was
>> fixed in an update to Stata 10 on 02apr2008 (see -help whatsnew10- and
>> search for "02apr2008").
>>
>>
>> -- Phil
>>
>> *
>> * 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/
>>
>
*
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