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From | Jonah Rexer <jorexer@gmail.com> |
To | statalist@hsphsun2.harvard.edu |
Subject | Re: st: Unique Randomization within groups |
Date | Thu, 31 Jan 2013 15:37:11 +0300 |
I tried that before, but I can't set an obs lower than 99 on my version of stata. Is this normal? On Thu, Jan 31, 2013 at 3:25 PM, Nick Cox <njcoxstata@gmail.com> wrote: > Abstracting from the complicated context > > clear > set obs 3 > set seed <whatever> > gen y = runiform() > sort y > gen wanted = _n > > gives you -wanted- that is 1, 2, 3. Which observations are assigned 1, > 2, 3 is random by virtue of shuffling according to previously > generated random numbers. So use the sort order, not the random > numbers themselves. > > (There still is a minute probability of ties. I wouldn't expect that > to bite in practice.) > > On Thu, Jan 31, 2013 at 12:14 PM, Jonah Rexer <jorexer@gmail.com> wrote: >> Hello, >> >> I am doing a randomization among 3 groups (2 treatment and 1 control) for a >> micro experiment. >> Our sample is small, N=99 with the unit being a cluster (a group of 2-3 >> respondents). >> I have merged clusters to assign each a random number. But instead of >> stratifying, since our sample is so small, I have organized each cluster >> into a group of 3 clusters (so 33 groups, each with 3 clusters) based on >> our stratification variables. >> >> What I want to do is assign a random integer, 1-3, within each group. I've >> used the command: >> >> set seed 4109 >> >> bysort cluster_group : gen random1=floor((3-1+1)*runiform()+1) >> >> The problem is that this doesn't give me a unique number. Within each >> group, i need one observation (cluster) to be 1, one to be 2, and one to be >> 3. This is why I used bysort, but it doesn't seem to be making any >> difference. Is there any way to ensure that the number assigned is unique >> within the group? > * > * For searches and help try: > * http://www.stata.com/help.cgi?search > * http://www.stata.com/support/faqs/resources/statalist-faq/ > * http://www.ats.ucla.edu/stat/stata/ -- Jonah Rexer Research Fellow BRAC Uganda Plot 90, Busingiri Zone, Nyanama Kampala, Uganda www.brac.net * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/faqs/resources/statalist-faq/ * http://www.ats.ucla.edu/stat/stata/