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Re: st: Cox Regression - flat region resulting in a missing likelihood

To   Statalist <>
Subject   Re: st: Cox Regression - flat region resulting in a missing likelihood
Date   Tue, 30 Apr 2013 09:25:58 +0800

One other option is a convergence trick from 'Methods for estimating
adjusted risk ratios' by Peter Cummings, The Stata Journal (2009) 9,
Number 2, pp. 175–196.

It's the last paragraph on pg 180.

On Tue, Apr 30, 2013 at 8:04 AM,  <> wrote:
> Theresa writes:
>> I set my data stset and then I tried to run a stcox and got the following
>> error message " flat region resulting in a missing likelihood r(430)";
> I would first try to change the settings for ties (Efron, exactp,
> exactm) if you have many tied failure times.
> Beyond that, it likely due to so-called 'mono-tone' likelihood;
> there's a solution called the Firth method. Unfortunately, it is not
> implemented in Stata for Cox models (but is in Some Alternative
> Software and in R).
> You could also try to randomize your times slightly (which likely
> won't work); use flexible parametric models which will require some
> startup (-ssc install stpm2-); or do a Poisson regression to get
> (essentially) the same coefficients as Incident Rate Ratios instead of
> HRs. Best source of how to do this is Dupont's 'Statistical Modeling
> for Biomedical Researchers'.
> cheers-
> Andrew Lover
> ______________________________________________
> Epidemiologist
> Centre for Infectious Disease Epidemiology Research (CIDER)
> Saw Swee Hock School of Public Health
> National University of Singapore

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