[R] what is the difference between survival analysis and (...)

[Frank E Harrell Jr]

Eric Elguero wrote:
> Hi everybody,
> 
> recently I had to teach a course on Cox model, of which I am
> not a specialist, to an audience of medical epidemiologists.
> Not a good idea you might say.. anyway, someone in the
> audience was very hostile. At some point, he sayed that
> Cox model was useless, since all you have to do is count
> who dies and who survives, divide by the sample sizes
> and compute a relative risk, and if there was significant
> censoring, use cumulated follow-up instead of sample
> sizes and that's it!
> I began arguing that in Cox model you could introduce
> several variables, interactions, etc, then I remembered
> of logistic models ;-)
> The only (and poor) argument I could think of was that
> if mr Cox took pains to devise his model, there should
> be some reason...

That is a very ignorant person, concerning statistical 
efficiency/power/precision and how to handle incomplete follow-up 
(variable follow-up duration).  There are papers in the literature (I 
wish I had them at my fingertips) that go into the efficiency loss of 
just counting events.  If the events are very rare, knowing the time 
doesn't help as much, but the Cox model still can handle censoring 
correctly and that person's approach doesn't.

Frank

> 
> but the story doesn't end here. When I came back to my office,
> I tried these two methods on a couple of data sets, and true,
> crude RRs are very close to those coming from Cox model.
> 
> hence this question: could someone provide me with a
> dataset (preferably real) where there is a striking
> difference between estimated RRs and/or between
> P-values? and of course I am interested in theoretical
> arguments and references.
> 
> sorry that this question has nothing to do with R
> and thank you in advance for your leniency.
> 
> Eric Elguero
> GEMI-UMR 2724 IRD-CNRS,
> Équipe "Évolution des Systèmes Symbiotiques"
> 911 avenue Agropolis, BP 64501,
> 34394 Montpellier cedex 5 FRANCE
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
> 


-- 
Frank E Harrell Jr   Professor and Chair           School of Medicine
                      Department of Biostatistics   Vanderbilt University