Michael--
I don't understand your example data--is that correctly stated? Do
you want to select with replacement or without? The general problem of
selecting for each observation a random subset of N other cases that
satisfy some condition is fairly easy, though, if you generate a
random number u, sort by u, then select the first N matching cases.
On Dec 24, 2007 2:11 PM, Michael McCulloch <[email protected]> wrote:
> Dear Statalist members,
>
> I would like to ask help in a routine for selecting random matched
> controls in a survival dataset.
>
> I have patients (tx=1) and controls (tx=0), and have _stset_.
> Time from diagnosis to death = _t.
> In the patients, I also know the time between diagnosis and treatment
> (leadtime).
>
> I wish to randomly select two controls per patient, from among all
> controls who have survived at least as long as the leadtime for that
> patient. For example, subject ID==1 has eligible controls:
> ID==12 | ID==13 | ID==14
> Therefore, I'd like to randomly select two controls from among those
> three eligible controls.
>
> ID tx _t leadtime
> 1 1 1.0 0.4
> 2 1 1.2 0.3
> 11 0 0.1
> 12 0 0.9
> 13 0 1.1
> 14 0 0.5
>
> May I ask how this can be done in a do-file or small program?
>
> Happy Holidays to all,
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