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From |
"Kaganova, Yevgeniya M." <YKAGANOVA@PARTNERS.ORG> |

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

Subject |
RE: st: Using weights from the Current Population survey |

Date |
Mon, 22 Jul 2002 10:27:55 -0400 |

> -----Original Message----- > From: Lee Sieswerda [SMTP:Lee.Sieswerda@tbdhu.com] > Sent: Wednesday, July 03, 2002 2:24 PM > To: 'statalist@hsphsun2.harvard.edu' > 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 > Lee.Sieswerda@tbdhu.com > www.tbdhu.com > > > > > -----Original Message----- > > From: David Kantor [SMTP:dkantor@jhu.edu] > > Sent: Wednesday, July 03, 2002 1:53 PM > > To: statalist@hsphsun2.harvard.edu > > 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 > > dkantor@jhu.edu > > 410-516-5404 > > > > * > > * For searches and help try: > > * http://www.stata.com/support/faqs/res/findit.html > > * http://www.stata.com/support/statalist/faq > > * http://www.ats.ucla.edu/stat/stata/ > * > * For searches and help try: > * http://www.stata.com/support/faqs/res/findit.html > * http://www.stata.com/support/statalist/faq > * http://www.ats.ucla.edu/stat/stata/ * * For searches and help try: * http://www.stata.com/support/faqs/res/findit.html * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

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