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# Re: st: Question on interpretation of survey data: from the mean to the total

 From Laurie Molina To statalist@hsphsun2.harvard.edu Subject Re: st: Question on interpretation of survey data: from the mean to the total Date Sun, 12 Sep 2010 22:22:17 -0500

Thank you all very much.
Exactly what i was looking for.
Regards,
LM

On Sun, Sep 12, 2010 at 10:01 PM, Stas Kolenikov <skolenik@gmail.com> wrote:
> I would go with
>
> svy : mean cars
>
> and
>
> svy : total cars if (household_head)
>
> if "cars" is the variable where the number of cars in the HH is
> stored. It does not matter what was the purpose of the data
> collection, but you need to have a clear notion of the units of
> sampling, weighting, and analysis. If the latter matches the ave #
> cars times expanded # of HHs, that's great, but you won't be able to
> get the standard errors around it. With the above syntax, you will.
>
> On Sun, Sep 12, 2010 at 8:09 PM, Laurie Molina <molinalaurie@gmail.com> wrote:
>> In my dataset each observation is a household and the weights are for
>> households.
>> In the survey there is a question about the number of cars of the household.
>> So i am interested in the average number of cars of the HH.
>> An also i am interested in the total number of cars owned by HH.
>>
>> To my understand it is ok to calculate the average number of cars of
>> the HH, even with
>> summarize cars[weight=factor].
>>
>> But if i get that mean, and i multiply it by the (expanded) number of
>> observations (HH), is it ok to say that it is the total number of cars
>> of the HH in the survey?
>>
>> Thank you very much again!
>>
>>
>> On Sun, Sep 12, 2010 at 7:13 PM, Steve Samuels <sjsamuels@gmail.com> wrote:
>>> --
>>>
>>>  In advance I would say that you should create a data set in which
>>> each observation is a HH and the weight is an appropriate HH weight.
>>> However to advise you further with some assurance, we  would need to
>>> know how the weights were computed-was there post-stratification or
>>> "raking", for example and details about the design (clusters, stages
>>> is too vague). including the -svyset- statement.  Your current
>>> approach is almost certainly wrong, because the denominator for -svy:
>>> mean- will be individuals, not HH; it will be biased, because larger
>>> HH will contribute more observations.
>>>
>>> Steve
>>>
>>> Steven J. Samuels
>>> sjsamuels@gmail.com
>>> 18 Cantine's Island
>>> Saugerties NY 12477
>>> USA
>>> Voice: 845-246-0774
>>> Fax:    206-202-4783
>>>
>>>
>>>
>>> On Sun, Sep 12, 2010 at 2:50 PM, Laurie Molina <molinalaurie@gmail.com> wrote:
>>>> Dear all,
>>>> I have a question on the interpretation of survey data.
>>>> There is a survey in which the analysis units are the households and
>>>> its members.
>>>> Using the command svyset i have set the design characteristics of the
>>>> survey: clusters, two stages, stratification and probabilistic.
>>>> And i have asked stata for the mean of the number of cars in the households.
>>>> Is it all right if i multiply the mean of the number of cars in the
>>>> households by the expanded number of households to get the total
>>>> number of cars of the households?
>>>> Or does it depend on wheter the survey was designed to get the total
>>>> number of cars of the households?
>>>> Thank you very much in advance.
>>>> Laurie
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>>
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>
>
>
> --
> Stas Kolenikov, also found at http://stas.kolenikov.name
> Small print: I use this email account for mailing lists only.
>
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