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RE: st: Using weights from the Current Population survey
> -----Original Message-----
> From: Lee Sieswerda [SMTP:Lee.Sieswerda@tbdhu.com]
> Sent: Wednesday, July 03, 2002 2:24 PM
> To: 'firstname.lastname@example.org'
> Subject: RE: st: Using weights from the Current Population survey
> A better option than using iweight or aweight with -tabulate- is to use
> -svytab- and pweight. It has several advantages, one of which is that gives
> you asymptotic 95% CIs that will not cross 0 or 1 (which is good because you
> can't have less than 0 people enter a survey response, nor more than 100%).
> And to head off the next question, -svytab- won't allow you to specify only
> one variable in the command statement. If you want to tabulate the responses
> to a single question you have to create a constant (e.g., gen dum=1) and use
> it as your second variable, as in:
> svytab q1 dum, [options - lots of them]
> Also, make sure you use the -subpop- option to specify subpopulations, not
> -if- or -in-.
> And finally, you absolutely have to use the weights provided if you want the
> results to be representative of the population and not just the sample. I
> don't know about the CPS specifically, but it is unlikely that you'll be
> provided with the psu and strata information because in well-conducted
> surveys the clusters sampled are usually quite small and it would be
> possible for a determined analyst to identify individuals - especially in
> lightly-populated areas. To get around this problem in Canada, at least, for
> large government surveys we are provided with a data set of bootstrap
> weights from which to calculate bootstrapped standard errors. If you do not
> have access to the psu and strata information, then you might enquire if
> such a beast is available for the Current Population Survey.
> Best regards,
> Lee S.
> Lee Sieswerda, Epidemiologist
> Thunder Bay District Health Unit
> 999 Balmoral Street
> Thunder Bay, Ontario
> Canada P7B 6E7
> Tel: +1 (807) 625-5957
> Fax: +1 (807) 623-2369
> > -----Original Message-----
> > From: David Kantor [SMTP:email@example.com]
> > Sent: Wednesday, July 03, 2002 1:53 PM
> > To: firstname.lastname@example.org
> > Subject: Re: st: Using weights from the Current Population survey
> > At 12:18 PM 7/3/2002 -0500, Nammi Kandula wrote:
> > >I am doing an analysis with the MARCH current population survey.
> > >I am doing a person-level analysis.
> > >
> > >If I use the wgt varaible, stata asks me what kind of weight this is.
> > >Is it an analytic weight, pweight, fweight?
> > >
> > >Should I use the weight in my regressions, or in my tab commands. Do i
> > need
> > >to transform the weight in any way?
> > My experience is that all weights in surveys from the U.S. Census Bureau
> > are pweights.
> > You should specify them as pweights in regressions. (If you use them as
> > aweight, the coefficients will be the same, but the variances and
> > confidence intervals will be wrong. See the section in the user guide on
> > Estimation, Weighted Estimation; that's U 26.12 in my ancient V5 manual.)
> > Better -- use svyreg and specify the strata and psu, if these are
> > identified. Still, specify the weight as pweight.
> > For -tabulate-, pweight is not accepted. Use aweight or iweight; the
> > proportions will not be affected by the choice, but iweight has the
> > advantage that the "Freq." will be the weighted sums of the observations
> > --
> > i.e., the estimated number of actual population in the given category. Be
> > sure you have scaled the weight correctly at the outset, if there are any
> > implied decimals in the raw data.
> > I hope this helps.
> > -- David K.
> > David Kantor
> > Institute for Policy Studies
> > Johns Hopkins University
> > email@example.com
> > 410-516-5404
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