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Re: st: sample


From   Richard Williams <[email protected]>
To   [email protected]
Subject   Re: st: sample
Date   Thu, 16 Dec 2004 06:52:15 -0500

At 11:09 AM 12/16/2004 +0100, Hans J.  Baumgartner wrote:
Dear statalist,

Has anybody on the list some experience to share on drawing a random sample?

How important is it that the data is not sorted before the sample is drawn? Which mistakes can be made? Etc.

I am using the following command:

set seed 123456789
sample 4000, count

What is the set seed making really and which impact has the number I am setting?
I think the main thing set seed does is make sure you can re-draw the same random sample if you want to. Or, alternatively, make sure you draw a different random sample. I don't know why it would matter if the data is sorted or not; if you were drawing a systematic sample (e.g. selecting every 10th case) then sorting could have the effect of stratifying the sample, I guess.


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Richard Williams, Notre Dame Dept of Sociology
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