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From |
"Lynn Lee" <lynn09v@gmail.com> |

To |
<statalist@hsphsun2.harvard.edu> |

Subject |
st: sampling weight |

Date |
Thu, 27 Sep 2012 10:58:07 +0800 |

Dear Stas, I just want to do simple sampling. Take "webuse total" for example. I am wondering how was "swgt" generated? I guess: obs 1 has her corresponding sampling weight, swgt=25964, which is the total population in her group; obs 4 has his corresponding sampling weight, swgt=4312, which is the total population in his group;etc. Is that right? So, if I use this logic in my downloaded survey data sets, I can group all the obs into different sampling weight over residence place and gender. Like: I calculate total number of individuals who were in the dataset according to their resident city , say, total number of individuals in city 1 is 1000 in dataset, total number of individuals in city n is 400 in the data set, then, I generate this city-total-individuals as a new variable (weight). (Or I can even be more detailed, total number of people in the data set over city, gender, age.) In regression, I simply use command "reg y x1 x2 x3 [pweight=total]". Can this way correct in part for unweighted data set? Suppose the mean of total(weights) is 500, min is 100 and max is 800.Then, weighted analysis will give at most 800/100 times the weights to potentially under-sampled observations. Do I understand correctly? I appreciate for your suggestion in advance. Best Regards, Lynn Lee -----Original Message----- From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Stas Kolenikov Sent: Wednesday, September 26, 2012 9:44 PM To: statalist@hsphsun2.harvard.edu Subject: Re: st: sampling weight If Lynn obtained her sample in a rigorous way by enumerating the dwellings, she should have all the inputs into the probability of selection, and the baseline sampling weight is the inverse of that. Then she would want to correct for non-response, which would be the fraction of those responding to the survey among those sampled. If Lynn is interested in a specific population (females of reproductive age, say), and that's who the survey collected the data on, then she would need to get the total population counts for that specific population (which may prove even more difficult). If she does not have these figures, then I don't really know what to do. As they say, when you approach a statistician with collected data in hand, they can only tell you what killed your study. -- -- Stas Kolenikov, PhD, PStat (SSC) :: http://stas.kolenikov.name -- Senior Survey Statistician, Abt SRBI :: work email kolenikovs at srbi dot com -- Opinions stated in this email are mine only, and do not reflect the position of my employer On Wed, Sep 26, 2012 at 8:15 AM, JVerkuilen (Gmail) <jvverkuilen@gmail.com> wrote: > On Wed, Sep 26, 2012 at 2:49 AM, Lynn Lee <lynn09v@gmail.com> wrote: > >> Any suggestion to suggest which weight is better? Or, other types of weights >> may be better than population weights? > > Do you have a few accurately observed variables such as the population > age and gender breakdown? If so you can often create > post-stratification weights (through a process called "raking") that > make your samples align with the associations observed in those > tables. > > A quick -findit raking- turned up a program -ipfraking- written by > Stas Kolenikov and available from his website. Hopefully he'll chime > in. > * > * 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/

**Follow-Ups**:**Re: st: sampling weight***From:*Stas Kolenikov <skolenik@gmail.com>

**References**:**st: sampling weight***From:*"Lynn Lee" <lynn09v@gmail.com>

**Re: st: sampling weight***From:*"JVerkuilen (Gmail)" <jvverkuilen@gmail.com>

**Re: st: sampling weight***From:*Stas Kolenikov <skolenik@gmail.com>

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