Statalist


[Date Prev][Date Next][Thread Prev][Thread Next][Date index][Thread index]

st: random sample selection


From   "raoul reulen" <[email protected]>
To   [email protected]
Subject   st: random sample selection
Date   Tue, 1 Apr 2008 13:38:48 +0100

Hi Statalisters,

I am trying to get a random sample of 40 subjects from a dataset of a
few hundred subject. This is what I did:

.set seed 12345
.gen random = uniform()
.sort random, stable
.drop if _n>40


For various reasons, it might be that some subjects in the sample are
not suitable for selection and I want to exclude them from the sample
and from the overall dataset.

So I selected another sample, however, when I did that other subjects
were selected as well.

.drop if id == 890800  //subject that wasn't suitable dropped
.set seed 12345
.gen random = uniform()
.sort random, stable
.drop if _n>40


What I want is to keep the original 39 subjects as in the old sample
in  and just replace the subject that wasn't suitable. Any suggestions
would be appreciated.

Many thanks.

Raoul




-- 
-------------------------------------------------------
Raoul C. Reulen
Cancer Research UK Training Fellow
*
*   For searches and help try:
*   http://www.stata.com/support/faqs/res/findit.html
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/



© Copyright 1996–2024 StataCorp LLC   |   Terms of use   |   Privacy   |   Contact us   |   What's new   |   Site index