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From |
"Louise Linsell" <Louise.Linsell@npeu.ox.ac.uk> |

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

Subject |
Re: st: How to svyset when strata are used in some groups and not others |

Date |
Mon, 05 Jul 2010 10:06:39 +0100 |

Thank you for suggestions. We have already tried defining 9 strata; 6 for the common type of hospital, for which we used stratified random sampling with 6 strata, and 1 stratum each for the other 3 types of hospital, for which we took all units. However, in the model we had to specify a finite population correction (FPC=sqrt(1-n/N)) as we sampled 28 out of 87 units for the most common type of hospital. Because we sampled ALL the units from the other 3 types of hospital we had to set the FPC to zero since n=N (which is specified as 1 in Stata as it requires you to specify n/N). This means that there are no variance estimates when we summarise any outcomes in the 3 less common types of hospital, because it thinks we have sampled the whole population within these hospitals (when in fact we took a consecutive number of patients over a period of 3 months). LL >>> Stas Kolenikov <skolenik@gmail.com> 02/07/2010 20:36 >>> If Louise sampled other 3 types lumping them together, then Steve's recommendation is appropriate. If sampling was performed within each of those remaining types, then the strata variable will have 6 (strata in the most common type of hospitals) + 3 (other types of hospitals) = 9 levels. On Fri, Jul 2, 2010 at 11:18 AM, Steve Samuels <sjsamuels@gmail.com> wrote: > Louise-- create a stratum variable with 7 values: 1-6 for the > hospitals of the first type, and 7 for the other three types, and use > that in the strata() option of -svyset- > > Steve > > On Fri, Jul 2, 2010 at 12:00 PM, Louise Linsell > <Louise.Linsell@npeu.ox.ac.uk> wrote: >> I have a dataset with 4 different types of hospital, and would like to compare binary outcomes between them using logistic regression. However for the first type (the most common), hospitals were divided into 6 strata (based on size and SES) and a random sample was taken from each strata. For the other 3 types of hospital we sampled all hospitals. My question is, how to use the svyset command when a different sampling strategy was used in one group? >> >> LL >> >> >> >> >> * >> * 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/ >> > > > > -- > Steven Samuels > sjsamuels@gmail.com > 18 Cantine's Island > Saugerties NY 12477 > USA > Voice: 845-246-0774 > Fax: 206-202-4783 > > * > * 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/

**Follow-Ups**:**Re: st: How to svyset when strata are used in some groups and not others***From:*Steve Samuels <sjsamuels@gmail.com>

**References**:**st: How to svyset when strata are used in some groups and not others***From:*"Louise Linsell" <Louise.Linsell@npeu.ox.ac.uk>

**Re: st: How to svyset when strata are used in some groups and not others***From:*Steve Samuels <sjsamuels@gmail.com>

**Re: st: How to svyset when strata are used in some groups and not others***From:*Stas Kolenikov <skolenik@gmail.com>

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