Re: st: survival analysis vs ols

[=?UTF-8?B?Um9uw6FuIENvbnJveQ==?= <rconroy@rcsi.ie>]

Zhu, Carolyn wrote:

> Hello,
>
> We are trying to estimate the effect of ER room conditions on the time 
> it takes for patients to receive treatment A. All patients received 
> treatment A some time their ER admission so we don't have any right 
> censoring problem. I was just told that in this case survival analysis 
> and OLS give the same results. Is that correct?
>
> Thanks.
>
> Carolyn
Survival analysis has one great advantage here: you can the shape of the 
distribution of time to treatment as a nuisance parameter, something to 
be got out of the way before getting down to the real work. You can 
report quantiles of interest, and use the graphs available to very good 
effect.

Analysing times using OLS can be problematic. The distribution looks 
funny, and some people (not in your case) never make it. One solution 
that often gives quite an acceptable data distribution is to use the 
reciprocal of time, which has a common-sense interpretation: speed. 
People who never make it have a speed of zero.

--

Ronan M Conroy (rconroy@rcsi.ie) 
Senior Lecturer in Biostatistics 
Royal College of Surgeons 
Dublin 2, Ireland 
+353 1 402 2431 (fax 2764) 
-------------------- 
Just say no to drug reps 
http://www.nofreelunch.org/

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