Simulating data per subject per visit

[SR79]

Hi, 

I am trying to simulate a dataset for 100 subjects over the course of 10 days such that the variable y with normal distribution is repeating the same value within each subject per each day.

I have the following:

data A;

call streaminit(1);

do subject =1 to 100;

 do t = 1 to 10;

y=rand('normal',1,2);

output;

label t='Day';

end;

end;

 run;

which produces:

subject  day  y

1             1    1.03

1             2    3.02

....

2             1    1.45

2             2    0.39

...

etc.

I want this structure: 

subject  day  y

1             1    1.03

1             2    1.03

....

2             1    1.45

2             2    1.45

...

etc.

Any help is appreciated. 

Thank you! 

[mkeintz · Accepted solution]

So you want a normal distribution accross subjects, but no variation at all within subject, right?  

If so, then modify your program by taking the RAND function outside of the inner loop, and put it in the outer loop:

data A;
  call streaminit(1);
  do subject =1 to 100;
    y=rand('normal',1,2);
    do t = 1 to 10;
      output;
    end;
  end;
  label t='Day';
run;

[SR79]

Perfect thanks!!