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From |
Marta Garcia-Granero <[email protected]> |

To |
[email protected] |

Subject |
Re: st: Conditional logistic regression: how to |

Date |
Mon, 18 Nov 2013 10:25:57 +0100 |

Ah! Now I see. Shouldn't your final command be: mi estimate: clogit _case x1 x2, group(_set) HTH, Marta El 18/11/2013 10:11, Liliana Andriano escribió:

Thank you for your reply Marta. The fact is that I need to estimate the fixed effects logit regressions relying on conditional logits, also known as the case-control technique (Chamberlain, 1980), so I should randomly select pairs from each sample, consisting of one death reported during five years preceding the survey and one birth that still survived at the survey time. For this I have realized that the sttocc command in Stata allows you to convert survival-time data to case-control data, but before running it, the declaration of survival data is necessary. Do you know if I randomly select pairs from each sample even though I am not declaring survival data and then converting survival-time data to case-control data? Your help is very appreciated. Many thanks in advance. Best, Liliana 2013/11/18 Marta Garcia-Granero <[email protected]>:Hi Liliana: Maybe I am missing something, because I'm no Stata expert. As a former SPSS user, a program that did not have a specific command for conditional logistic, I used the well known trick of using survival analysis (Cox) instead. Since Stata has -clogit-, I don't think you need to declare survival data before running it. See this simple example (maybe too simple) where -clogit- and -stcox- outputs are exactly the same. * Sample data from www.hrc.es/bioest/Reglog_9.html (coding for hepat had to be reversed!!) * input hepat alcoh drug stratum 1 15 1 1 0 10 0 1 0 0 0 1 1 70 1 2 0 20 0 2 0 30 0 2 1 40 1 3 0 40 0 3 0 0 0 3 1 10 0 4 0 20 1 4 0 50 0 4 1 30 1 5 0 10 0 5 0 20 0 5 1 80 0 6 0 20 0 6 0 30 0 6 1 50 1 7 0 35 0 7 0 10 0 7 1 60 1 8 0 5 0 8 0 10 0 8 1 90 0 9 0 65 0 9 0 5 0 9 1 30 1 10 0 10 0 10 0 40 0 10 end * Using clogit * clogit hepat c.alcoh i.drug c.alcoh#i.drug, group(stratum) or * using Cox * gen ptime=1+(hepat==0) stset ptime, failure(hepat==1) stcox c.alcoh i.drug c.alcoh#i.drug, strata(stratum) I hope this helps Marta García-Granero, PhD Dpt. of Biochemistry and Genetics, University of Navarra El 14/11/2013 15:59, liliana escribió:Dear statlist users, I am trying to run a conditional logistic regression. The analysis consists of studying the determinants of child mortality. Before running the conditional logistic regression I should randomly select pairs from each sample, consisting of one death reported during five years preceding the survey and one birth that still survived at the survey time. Moreover, I have also imputed the missing values of an explanatory variables, which means that before the stata command I should insert the mi estimate: option. What I have done in Stata is set seed 8021 then I have declared my data to be survival data and then sttocc, match(mortality), where mortality is a dummy variable assuming value 0 if the child died during five years preceding the survey. Then I go with: mi estimate: clogit y x1 x2, group(_set) Stata tells me that (regular variables _st _d _t _t0 unregistered because not in m=0) groups (strata) are not nested within clusters an error occurred when mi estimate executed clogit on m=1 r(459); May you tell me what's wrong with these commands, please? Thank you very much. Best, Liliana -- View this message in context: http://statalist.1588530.n2.nabble.com/Conditional-logistic-regression-how-to-tp7580452.html Sent from the Statalist mailing list archive at Nabble.com. * * 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/

* * 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: Conditional logistic regression: how to***From:*Liliana Andriano <[email protected]>

**References**:**st: Conditional logistic regression: how to***From:*liliana <[email protected]>

**Re: st: Conditional logistic regression: how to***From:*Marta Garcia-Granero <[email protected]>

**Re: st: Conditional logistic regression: how to***From:*Liliana Andriano <[email protected]>

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