topic Re: question about using rand function in SAS Procedures

question about using rand function

pma85 — Mon, 07 May 2012 17:09:36 GMT

I'm trying to generate a data set with 1,000 observations with random integers from 1 to 5. Does anyone know how I would do this using the rand function?

Here's the question posed:

Create a temporary SAS data set (Random) consisting of 1,000 observations, each

with a random integer from 1 to 5. Make sure that all integers in the range are

equally likely. Run PROC FREQ to test this assumption

Re: question about using rand function

Linlin — Mon, 07 May 2012 17:22:37 GMT

try this:

data have;

do i=1 to 1000;

x=int(rand('uniform')*5)+1;output ;end;

run;

proc freq;

tables x/missing;

run;

Cumulative Cumulative

x Frequency Percent Frequency Percent

1 200 20.00 200 20.00

2 216 21.60 416 41.60

3 203 20.30 619 61.90

4 187 18.70 806 80.60

5 194 19.40 1000 100.00

Re: question about using rand function

PGStats — Mon, 07 May 2012 17:30:36 GMT

or x = ceil(5*rand("UNIFORM"));

Re: question about using rand function

pma85 — Mon, 07 May 2012 17:33:49 GMT

THank you very much!!

Re: question about using rand function

data_null__ — Mon, 07 May 2012 17:55:41 GMT

I would use table distribution but what do I know.

rand('TABLE',.2,.2,.2,.2);

Most useful I suppose if you want to fiddle with the probs.

Re: question about using rand function

Howles — Tue, 08 May 2012 14:12:09 GMT

One method which assures exactly equal likelihoods:

data notrandom ;

do val = 1 to 5 ; do rep = 1 to 200 ;

order = ranuni(2468) ;

output ;

end ; end ;

run ;

proc sort data=notrandom out=random(keep=val) ;

by order ;

run ;

proc freq data=random ; run ;

pma85 wrote:

I'm trying to generate a data set with 1,000 observations with random integers from 1 to 5. Does anyone know how I would do this using the rand function?

Here's the question posed:

Create a temporary SAS data set (Random) consisting of 1,000 observations, each

with a random integer from 1 to 5. Make sure that all integers in the range are

equally likely. Run PROC FREQ to test this assumption

Re: question about using rand function

PGStats — Tue, 08 May 2012 14:46:56 GMT

Howles, that technique generates a random ordering, not random values. Given any subset of 999 values from that set, the 1000th value is known without error. In other words, the values are not totally independent.