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From |
Antonio silva <asilva@inbox.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: logistic regression complex samples |

Date |
Wed, 7 Dec 2011 17:01:24 -0800 |

Thanks for the replies. I can run a model using SAS surveylogistic without the cluster variable but I have had difficulties to do the same with Stata version 11. I am a beginner in Stata programming.My final goal is to calculate the Archer and Lemeshow (A-L; 2006) goodness of fit test (with estat gof command) that is not available in SAS. To do that I have to run correctly the logistic regression model (with only weight and strata without cluster) in Stata. I hope someone can help with the Stata code. Consider the following code (ex. with 2 categorical covariates) that have been used and the output . svyset [pweight= var_weight], strata(var_strata) . xi: svy: logistic outcome i.covar1 i.covar2_3cat i.covar1 _Icovar1_1-2 (naturally coded; _Icovar1_1 omitted) i.covar2_3cat _Icovar2_3_1-3 (naturally coded; _Icovar2_3_1 omitted) (running logistic on estimation sample) Survey: Logistic regression Number of strata = 9 Number of obs = 398 Number of PSUs = 398 Population size = 4361.1088 Design df = 389 F( 0, 389) = . Prob > F = . ------------------------------------------------------------------------------ | Linearized outcome | Odds Ratio Std. Err. t P>|t| [95% Conf. Interval] -------------+---------------------------------------------------------------- _Icovar1_2 | 1.926984 . . . . . _Icovar2_~2 | .2875105 . . . . . _Icovar2_~3 | .1978389 . . . . . ------------------------------------------------------------------------------ Note: missing standard errors because of stratum with single sampling unit. Thanks, Antonio. > -----Original Message----- > From: skolenik@gmail.com > Sent: Wed, 7 Dec 2011 11:18:37 -0600 > To: statalist@hsphsun2.harvard.edu > Subject: Re: st: logistic regression complex samples > > Antonio, > > it would help if you mentioned the version of Stata that you are > using. By default, Stata would use observations as PSUs (and the > output of -svyset- would state that -- again, it would help if you > included the output of both commands). You can also achieve the effect > of specifying observations as PSUs via -svyset _n ...-. > > On Wed, Dec 7, 2011 at 10:05 AM, Antonio silva <asilva@inbox.com> wrote: >> Hello, >> I would like to perform binary logistic regression in stratified >> sampling incorporating 2 variables that represents that design >> var_weight and var_strata. >> Considering a model with 2 covariates , in SAS I would consider a code >> like this that works perfectly: >> >> PROC SURVEYLOGISTIC DATA = dataset >> STRATA var_strata; >> >> WEIGHT var_weight; >> >> >> CLASS covariate1 >> Covariate2 ; >> >> MODEL outcome(event='1')= covariate1 covariate2 /clparm vadjust=none ; >> Run; >> >> >> I tried an equivalent Stata code but does not work. It seems that in >> Stata its is always necessary have the cluster variable. But in my >> design I do not have cluster variable,only weight and strata. >> >> svyset [pweight= var_weight], strata(var_strata) >> >> svy: logistic outcome i.covariate1 i.covariate2 >> >> After run , in the output appears only the OR calculated and a note: >> Note: missing standard errors because of stratum with single sampling >> unit. >> What is wrong with it? >> >> After that I did some tests considering a fictitious cluster variable >> and worked. I suppose this command works only when the 3 design >> variables weight strata and cluster are used at the same time. > > -- > 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/ ____________________________________________________________ Share photos & screenshots in seconds... TRY FREE IM TOOLPACK at http://www.imtoolpack.com/default.aspx?rc=if1 Works in all emails, instant messengers, blogs, forums and social networks. * * 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: logistic regression complex samples***From:*Steve Samuels <sjsamuels@gmail.com>

**Re: st: logistic regression complex samples***From:*Stas Kolenikov <skolenik@gmail.com>

**References**:**Re: st: logistic regression complex samples***From:*Stas Kolenikov <skolenik@gmail.com>

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