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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 20:09:10 -0500

```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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```