topic How to create a random sample with seeds of time + minute + second ? in SAS Programming

How to create a random sample with seeds of time + minute + second ?

HappySASUE — Wed, 24 Apr 2019 02:34:13 GMT

Hi I need to create 1000 samples for simulation study. Does any one know how to create a random sample with seeds of time + minute + second ? Thanks

Re: How to create a random sample with seeds of time + minute + second ?

PGStats — Wed, 24 Apr 2019 02:45:43 GMT

Can you explain further what you mean by "with seeds of time + minute + second"?

If you want the pseudo random number seed to be based on the computer clock you can 1) omit to set a seed or 2) set the seed to a negative number.

Re: How to create a random sample with seeds of time + minute + second ?

HappySASUE — Wed, 24 Apr 2019 03:07:40 GMT

Sure.

I need to run 1000 times, however with the current code, they all have the same seed = 12345. I want to create a macro variable which change every time I pull the sample. One idea is to set the seed macro variable as the time we create the samples.

for example for the first iteration: if time is 10am 1 minute 1 second then %let seed = 100101; second iteration seed become 100111 if each simulation takes 10 seconds. I remember SAS has a function of current time...system....I forget. It create a macro variable of the current time.

Thanks

%macro uniform(datain =, dataout =, size = );
/*pulling a random sample from original data*/
data &dataout. (drop=obsleft sampsize);
sampsize= &size.;
obsleft=totobs;
do while(sampsize>0);
pickit+1;
if ranuni(12345)<sampsize/obsleft then do;
set &datain. point=pickit
nobs=totobs;
output;
sampsize=sampsize-1;
end;
obsleft=obsleft-1;
end;
stop;
run;

%mend uniform;

Re: How to create a random sample with seeds of time + minute + second ?

PGStats — Wed, 24 Apr 2019 03:13:32 GMT

If datain is always the same, you should use proc surveyselect with option reps=1000.

To get a different seed on every iteration, just omit setting the seed yourself. SAS will use the system clock by default.

Re: How to create a random sample with seeds of time + minute + second ?

HappySASUE — Wed, 24 Apr 2019 03:20:46 GMT

I see.. How about "call streaminit(321)"? Does it use seed 321 for 1000 iterations?

Re: How to create a random sample with seeds of time + minute + second ?

PGStats — Wed, 24 Apr 2019 03:28:40 GMT

That would reset the seed to 321 at every execution of the datastep.

Re: How to create a random sample with seeds of time + minute + second ?

HappySASUE — Wed, 24 Apr 2019 03:32:18 GMT

Understand. Thank you!