Date: Tue, 30 Mar 2010 09:23:23 0500
ReplyTo: Joe Matise <snoopy369@GMAIL.COM>
Sender: "SAS(r) Discussion" <SASL@LISTSERV.UGA.EDU>
From: Joe Matise <snoopy369@GMAIL.COM>
Subject: Re: Assigning random numbers
InReplyTo: <e8b6ac80c02b4a2cbdb34c439f362bbb@a1g2000vbl.googlegroups.com>
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1. sounds like a case for PROC SURVEYSELECT to me.
2. depends on the real world use case, I think. If this is a learning
problem then I'd think about why you will ultimately be using this kind of
thing; if it is an actual real world case then you probably should provide
more information, as IANAS but I suspect that there are possible reasons to
either go with one out of 6 possibilities (to ensure all 6 are used at least
once) or not.
If you don't end up using PROC SURVEYSELECT for the second, your basic
construction is:
x = ranuni(seed);
if x < proportion then ...;
else if x < 2*proportion then ... ;
...
else ;
where seed = some number you set or 0 for system timer assigned [I prefer
not to use 0 as it is not repeatable; choose something that is somewhat
random but is known, such as the current day, and then save it]. If you
know how to use SELECT/WHEN then that's actually better than if/else here
but both work fine.
If you end up needing to do the first by hand, there is a good page on the
sas community wiki on how to use k/n sampling; I don't recall the complete
solution but it's something like "if ranuni(seed) < k/n where k=remaining
sample needed n=remaining population available then select this record".
Joe
On Tue, Mar 30, 2010 at 8:37 AM, Winter <laura.e.dodge@gmail.com> wrote:
> Hi, there are two things I am trying to do with random numbers that I
> am having trouble with. Can anyone help me get started? Everything
> I've read online has been pretty complex...
>
> 1. I have 15 people who need to be assigned to either task 1, 2, or 3.
> They will only do one task and I want equal group sizes.
>
> 2. I have 10 people who will be doing all three tasks, but the order
> in which they do them needs to be randomly assigned (1,2,3 or 1,3,2
> etc.). Here the number of people doesn't matter since there are six
> possible orders. Do I need to make this like the previous problem
> where I would basically assign the 10 people to condition 16, or is
> there a way to get SAS to do the ordering itself?
>
> Thanks so much for the help!
>
