Re: st: sample

[Richard Williams <Richard.A.Williams.5@nd.edu>]

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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