trying to understand RANUNI

[Santt0sh]

Hi All,

I am trying to understand the RANUNI function. Trying to create a dataset using RANUNI  

For Ex. I have a Dataset ACCOUNTS having the below-mentioned variables

ACCT_NUM, AFLAG RF1, RF2, RF3, RF4 rf2cnts

0000000001    0            0     1        1      1       1

0000000004    0            1     1        1      1      1

0000000005    0            0     0        0     1       0 

000000300     0            0    0       0       0        0

I am using the below code to get a size and assign 1 rf2,rf3, and rf4 respectively if the value is 1  in a new variable (for eg. rfn) 

data rf2 (drop = x n);

set accounts;

n = ranuni(5);

retain x 1;

if rfcnts eq 1 and x = 10 then do;  * x = 10 number of rf2 needed with 1;

        rf2f = 1;

        x+1;

end;

else do;

   rf2f = 0;

end;

run;

I am trying to understand when I run the same data step on the same dataset will the value of N change, have tried running the data step on the same dataset a couple of times but every 10-15 mins I still see the value of N is same. is this how it should be or change every time I run the data step with RANUNI in it and on the same dataset with the same values and size?

Kindly note I don't want to use SurveySelect, please see the output attached where we have unchanged values of N.

Kindly suggest.

Regards,

S

[Tom]

If you run the data step using the same SEED you should get the set series of random numbers.

If that is not what you want then use a different SEED value for each run.

[FreelanceReinh · Accepted solution]

Hi @Santt0sh,

If you want n to change in virtually every run of the program, you can use the seed 0, i.e., n = ranuni(0). Then "the time of day is used to initialize the seed stream" (documentation), hence the automatic change. From the resulting random numbers (if you do not drop n from dataset RF2) you can even determine a non-zero seed that can be used to reproduce the same results, if needed.

(See also: Six reasons you should stop using the RANUNI function to generate random numbers.)

[Santt0sh]

Thank You for your quick response and this was helpful.