Re: st: inconsistent random numbers even using -set seed-

["Seed, Paul" <paul.seed@kcl.ac.uk>]

Thank you also to Phil Schumm.  
(and Bill Gould for the original post that Phil links to).
That answers my second question.

-isid- is useful command that I have not come across before.
For those who don't know, it checks whether the specified variables uniquely identify the 
observations; and with the -sort- option carries out a genuinely unique sort.

I suppose the ideal code for my example is now 

***************************
* Example code showing solution 2*

version 11.2
set more off
sysuse auto, clear

bys rep78: su  price mpg

* Crucial change here
isid make, sort
set seed 1234
gen rand = runiform()

bys rep78 (rand) : keep if _n <= _N/2
bys rep78: su  price mpg

* End example *
***********************


Paul T Seed, Senior Lecturer in Medical Statistics, 
Division of Women's Health, King's College London
Women's Health Academic Centre, King's Health Partners 
(+44) (0) 20 7188 3642.


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