topic Re: How to assign random numbers 1, 2, 3 to subjects in SAS Procedures

How to assign random numbers 1, 2, 3 to subjects

deleted_user — Wed, 06 Jan 2010 23:28:55 GMT

Hello,

I want to assign random numbers 1, 2, 3 to subjects in a dataset. Not sure how to use RANUNI function. Please help.

Thanks,
/Sukanya

Re: How to assign random numbers 1, 2, 3 to subjects

data_null__ — Thu, 07 Jan 2010 00:17:30 GMT

I'm not sure I understand your question. If you want to assign dummy treatments to a list(data set) of subjects that is easily done using the RANTBL function.

[pre]
trt = rantbl(seed,1/3,1/3);
[/pre]

This assigns one of three values 1,2,3 with equal probability for each. I use this technique to create dummy treatments when working to data that is still blinded.

If you need something more complex like generating a plan that can be done too.

Re: How to assign random numbers 1, 2, 3 to subjects

deleted_user — Thu, 07 Jan 2010 03:54:00 GMT

Thanks for the quick reply.

Sorry I want to assign 0, 1, 2. How do I do that. How does Seed value controls ?

Thanks,
/Sukanya

Re: How to assign random numbers 1, 2, 3 to subjects

Patrick — Thu, 07 Jan 2010 12:09:35 GMT

ranuni() gives you uniform distributed random numbers between 0 and 1.

The seed is the starting point from where you start picking the random numbers out of a very very long list of numbers.

If you use '0' as seed then the system time is used as seed and so the starting point is different for every execution of your code - resulting in an always different set of random numbers.

To assign random numbers between 0 and 2 use the following line in a data step:

RandomNumber=floor(ranuni()*3);

HTH
Patrick

Re: How to assign random numbers 1, 2, 3 to subjects

data_null__ — Thu, 07 Jan 2010 16:59:20 GMT

> Thanks for the quick reply.
>
> Sorry I want to assign 0, 1, 2. How do I do that.
Subtract 1.

> How does Seed value controls ?
SAS has online Help. It will explain the SEED and how to use it better than I can.

>
> Thanks,
> /Sukanya

Re: How to assign random numbers 1, 2, 3 to subjects

deleted_user — Thu, 07 Jan 2010 19:13:08 GMT

Thanks All. This really helps. Now I understand how Seed value controls.

Re: How to assign random numbers 1, 2, 3 to subjects

Sandhya — Fri, 08 Jan 2010 17:28:50 GMT

Hi

Do you just want to assign random number or want to select samples from a big population.

If it is the second case use PROC SURVEYSELECT.

It is pretty straight forward.

Sandhya.

Re: How to assign random numbers 1, 2, 3 to subjects

deleted_user — Mon, 25 Jan 2010 22:23:17 GMT

No, I just want to assign the random number for each observation randomly.

/Sukanya