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st: Re:

From   Ronan Conroy <>
To   "statalist" <>
Subject   st: Re:
Date   Thu, 19 Jun 2003 10:11:38 +0100

on 18/06/2003 5:23 pm, roger webb at wrote:

> I need to run a Cox model on a very large cohort (of approximately
> 1.5 million subjects). Has anyone implemented a memory efficient
> routine that uses a sample from (as opposed to all) the individuals
> at risk?

There isn't really any problem running the whole lot. Stata's datafiles are
much smaller than you think, and you're probably not going to tax the memory
on anything but a pretty small machine.

That said, there is nothing to stop you taking a sample and running the
model - Stata will take samples from your dataset. But don't do it just
because you think the whole thing will be far too cumbersome to analyse.
This is exactly the sort of problem where Stata is fast.

Ronan M Conroy (
Lecturer in Biostatistics
Royal College of Surgeons
Dublin 2, Ireland
+353 1 402 2431 (fax 2764)


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