topic Re: Random Selection Using Proc Surveyselect in SAS Procedures

Random Selection Using Proc Surveyselect

Jeff_DOC — Thu, 31 May 2012 23:25:45 GMT

I need to generate a random sample from a given population. I am using proc surveyselect. The code that generates the sample runs the exact same time each week. If I do not specify a seed option the computer clock is used but since the timing is so close each run the results have far too much verlap week to week. Each observation has several numeric variables and I was thinking of using one of those as a "seed" but I'm not sure if this is the best way.

Would anyone have a bit of expert advice on a good way to move forward?

Thanks very much.

Re: Random Selection Using Proc Surveyselect

Ajay — Thu, 31 May 2012 23:43:18 GMT

Could you make a random number in a datastep, store it as a macro variable, then use that as the seed?

Here's a good read on the random number generator:

http://support.sas.com/documentation/cdl/en/lefunctionsref/63354/HTML/default/viewer.htm#p026ygl6toz3tgn14lt4iu6cl5bb.htm

Are you using method = srs? Another option would be to try the other sampling methods...

Re: Random Selection Using Proc Surveyselect

Jeff_DOC — Fri, 01 Jun 2012 21:54:48 GMT

Hi Ajay.

The total population is just over 14,000 and I am using surveyselect to sample .471.

The same observations seem to come up pretty frequently. Almost as if surveyselect assigns a random number and then begins selection at the same place it did on the previous run.

Should I be sorting the data prior to selection?

proc surveyselect data = incoming out = outgoing

method = srs

rate = .00471;

id var1 var2 var3;

run;