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From | Stas Kolenikov <skolenik@gmail.com> |
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 22:01:15 -0500 |
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 >>> * >>> * 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/ >>> >> >> * >> * 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/ >> > > * > * 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/ > -- Stas Kolenikov, also found at http://stas.kolenikov.name Small print: I use this email account for mailing lists only. * * 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/