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From | "Roger B. Newson" <r.newson@imperial.ac.uk> |
To | statalist@hsphsun2.harvard.edu |
Subject | Re: st: Population attributable fractions (PAFs) in discrete-time survival analysis. -punaf- |
Date | Mon, 22 Jul 2013 11:59:34 +0100 |
I hope this helps. Best wishes Roger Roger B Newson BSc MSc DPhil Lecturer in Medical Statistics Respiratory Epidemiology and Public Health Group National Heart and Lung Institute Imperial College London Royal Brompton Campus Room 33, Emmanuel Kaye Building 1B Manresa Road London SW3 6LR UNITED KINGDOM Tel: +44 (0)20 7352 8121 ext 3381 Fax: +44 (0)20 7351 8322 Email: r.newson@imperial.ac.uk Web page: http://www.imperial.ac.uk/nhli/r.newson/ Departmental Web page: http://www1.imperial.ac.uk/medicine/about/divisions/nhli/respiration/popgenetics/reph/ Opinions expressed are those of the author, not of the institution. On 22/07/2013 10:43, S.Jenkins@lse.ac.uk wrote:
As part of his reply to Angelo Belardi <angelo.belardi@unibas.ch>, Roger Newson <r.newson@imperial.ac.uk> wrote:A. You can indeed use -punaf- after -cloglog-. (Or you should be able to do so - let me know if you have any problems.) However, the interpretation of the attributable and unattributable fractions will then be similar to the interpretation of these parameters when you use - -punaf- after -logit- or -logistic-. It is probably not a good idea to use -punafcc- after -cloglog-. And -punafcc- should probably not be used after -logit- or -logistic-, except if your data are from a case-control study (for which -punafcc- was written). After a Cox regression, you may use either -punaf- or -punafcc-, depending on what kind of population unattributable and attributable fractions you wanted to estimate (ie my kind or Samuelson and Eider's kind).My understanding is that Angelo is using -cloglog- to fit the discrete-time proportional hazard model, i.e. the analogue of the Cox model - which is for continuous survival times -- for interval -censored survival time data. The estimated coefficients on the predictors from the -cloglog- model are exactly the coefficients from the underlying continuous time model, and exp(coeff) is the corresponding hazard ratio. Given this context, why is it not a good idea to use -punaf- after -cloglog-? Could you please clarify? Stephen ------------------ Stephen P. Jenkins <s.jenkins@lse.ac.uk> Please access the attached hyperlink for an important electronic communications disclaimer: http://lse.ac.uk/emailDisclaimer * * 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/
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