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From |
Michael Drazer <michaeldrazer@uchicago.edu> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: STATA and NHIS weight variables |

Date |
Mon, 20 Jul 2009 13:48:40 -0500 |

Steve, Stas, Joao, and Nick: thank you for the help.

Please correct me if this does not sound correct. Thanks again for the consideration and help, Michael On Jul 20, 2009, at 12:22 PM, Stas Kolenikov wrote:

That's terrible -- they have a 100k input file with 2200+ lines, but did not bother to put just one more line for the appropriate design specification! Here's my understanding of NHIS: the household was conducted, and data were collected for each person (by self or proxy reporting) producing the person file. The weights in the person file would essentially be the household weights. An adult was sampled to provide more detailed information; their weight will be higher than the person weight by the factor equal to (# of people in the household). All sampled adults should have reported on the cancer supplement, so the sample adult and the sample adult cancer data should have the same weights. What was it that you tried to achieve by merging the three files? My understanding is that you should've received almost a block-diagonal structure of your data: the variables from the person data go with the person(=household) weights, the variables from the sample adult and cancer data go with the sample adult weights, and the observations/variables do not overlap. Am I wrong? If you want to mix information from them in your analysis, then you will have a lot of missing data from the unsampled adults who did not provide the information for the sample and cancer data sets. If only do the analysis using the person data, you should use the wtfa weights from the person data. If your analysis uses sample adult and cancer data, you should use wtfa_sa weights. I expect that it will be impossible to meaningfully analyze the data from all three files simultaneously, but I will likely be wrong with this. On Mon, Jul 20, 2009 at 11:07 AM, Michael Drazer<michaeldrazer@uchicago.edu> wrote:Hello,I am new to STATA and am doing some work with a dataset that Icreated bymerging together the 2005 sample adult, person, and sample adultcancer NHISdatasets. I'm trying to construct an appropriate survey designstatement,but am not sure how to properly define the pweights for my dataset.According to the Sample Adult variable layout, the wtfa_sa weightshould beused for most sample adult analyses - I noticed, however, that theSampleAdult dataset also has values for the wtfa weight. All of the 98,649observations in my merged dataset have wtfa weights, but only those31,428observations in the sample adult/sample adult cancer datasets containwtfa_sa weights. My question is: to properly weigh this data,should I use astandard survey design statement, such as: svyset [pweight=wtfa],strata(stratum)psu(psu)even though it does not take into account the wtfa_sa weights, oris there abetter way to weigh this data?For additional info re: variable layouts in the NHIS data, see here(theVariable layout PDFs are informative in terms of a description ofthe wtfaand wtfa_sa variables - see the person layout for wtfa and eitherthe sampleadult or sample adult cancer layout for the wtfa_sa variable): http://www.cdc.gov/nchs/nhis/nhis_2005_data_release.htm Thanks in advance, Michael * * 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/

* * 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/

**References**:**st: STATA and NHIS weight variables***From:*Michael Drazer <michaeldrazer@uchicago.edu>

**Re: st: STATA and NHIS weight variables***From:*Stas Kolenikov <skolenik@gmail.com>

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