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From |
Steve Samuels <sjsamuels@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: RE: RE: Using command svy glm to obtain risk ratios |

Date |
Mon, 17 Feb 2014 20:40:39 -0500 |

Amena: I recently co-authored a paper for which I first ran -svy: poisson- and then -svy: glm, link(log) which failed in about 2 of 20 models. I found four or five instances in which the relative risks differed so much that we had to abandon the idea of the Poisson approach. In others, the CIs for the RR exceeded 1.0 We were able to get -svy: glm, link(log) to work by slight modification of the models. You still have not shown us the actual commands you ran and the problematic -svy: glm- output. Please do so. Right now we have no actual evidence of the problem.. The only difference that I can see in the output of -glm- and -svy: glm, with the "eform" option is that -glm- heads the coefficient table "Risk Ratio" whereas -svy: glm- has a heading "exp(b)", which is the same thing. Steve Samuels sjsamuels@gmail.com On Feb 17, 2014, at 6:30 PM, "Hussein, Mustafa (Mustafa Hussien)" <mhussei4@uthsc.edu> wrote: You are welcome! No, you should estimate your models with the -svy- prefix if you have complex survey data. Your code should look like: svy: glm depvar indepvar, fam(poisson) link(log) eform Using the -svy- prefix is equivalent to cluster robust estimation with pweights. So, in essence, the "robust" part of modified Poisson is taken care of when using the -svy- prefix. For more info on estimating model-based RRs using log-binomial, Poisson, and Cox models, see: Barros & Hirakata (2003). BMC Med Res Methodol 3(21). PMID: 14567763 Zou (2004). Am J Epidemiol 159:702–706. PMID:15033648 Hope that helps Mustafa ________________________________________ From: owner-statalist@hsphsun2.harvard.edu [owner-statalist@hsphsun2.harvard.edu] on behalf of Agunwamba, Amenah A., Ph.D. [Agunwamba.Amenah@mayo.edu] Sent: Monday, February 17, 2014 4:17 PM To: statalist@hsphsun2.harvard.edu Subject: st: RE: Using command svy glm to obtain risk ratios Thanks Mustafa, So if I just eliminated the "svy" command, I can still get weighted RRs? An example code might be: glm outcome predictor, fam(poisson) link(log) no log vce(robust) Thanks! * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/faqs/resources/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/faqs/resources/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/faqs/resources/statalist-faq/ * http://www.ats.ucla.edu/stat/stata/

**Follow-Ups**:**Re: st: RE: RE: Using command svy glm to obtain risk ratios***From:*jose maria pacheco de souza <jmpsouza@usp.br>

**References**:**st: RE: Using command svy glm to obtain risk ratios***From:*"Agunwamba, Amenah A., Ph.D." <Agunwamba.Amenah@mayo.edu>

**st: RE: RE: Using command svy glm to obtain risk ratios***From:*"Hussein, Mustafa (Mustafa Hussien)" <mhussei4@uthsc.edu>

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