SAS rand – Generate Random Numbers in a SAS Data Step

If you want to generate random numbers in a SAS data step, the easiest way is to use the SAS rand() function.

data k;
	do i = 1 to 10;
		rand_num = rand("Uniform");
		output;
	end;
run;

When working with data, sometimes it can be very useful to generate random numbers to be able to perform simulations or get a random sample of a dataset.

In SAS, we can generate random numbers easily. The SAS rand() function can return random numbers from different statistical distributions depending on how we want the resulting properties of our randomly generated dataset.

Generating Random Numbers in a Range Using SAS

Using SAS, we can generate random numbers uniformly in a range easily. By default, if we pass “Uniform” to the SAS rand() function, you will receive random numbers between 0 and 1.

To generate random numbers between 0 and 1, we can do so easily in the following SAS code.

data k;
	do i = 1 to 10;
		rand_num = rand("Uniform");
		output;
	end;
run;

To generate random numbers between numbers a and b, for example, 0 and 10, we need to add by a and then multiple the randomly generated number by the difference between a and b.

data k;
    a = 0;
    b = 10;
    do i = 1 to 10;
        rand_num = a + (b - a) * rand("Uniform");
        output;
    end;
run;

You will see that the numbers generated from this data step are all between 0 and 10.

     i      rand_num
1    1  9.4039006904	
2    2  0.2762846812	
3    3  9.4098080415	
4    4  8.4096989129	
5    5  7.4553070194	
6    6  0.1901044999	
7    7  8.8871195493	
8    8  8.6166257504	
9    9  8.9881443954	
10  10  0.5240682443

Generating Random Integers in a Range Using SAS

If you want to generate random integers in a range, there are 2 ways you can do it. Depending on your version of SAS, you can pass “integer” to the SAS rand() function, or you will need to use the SAS ceil() function.

If you have a version of SAS later than SAS 9.4M5, you can pass “integer”, as well as the bounds of your range to generate random integers in a range.

data k;
    a = 0;
    b = 10;
    do i = 1 to 10;
        rand_int = rand("integer",0,10);
        output;
    end;
run;

If you have a version of SAS earlier than SAS 9.4M5, you have to use the SAS ceil() function. We can modify our code from above to generate an integer in a range using the SAS ceil() function easily.

data k;
    a = 0;
    b = 10;
    do i = 1 to 10;
        rand_num = a + ceil((b - a) * rand("Uniform"));
        output;
    end;
run;

As you can see below, we generate 10 integers between 0 and 10

     i  rand_num   
1    1         7	
2    2         9	
3    3         9	
4    4	       4	
5    5	       4	
6    6	       5	
7    7	       6	
8    8	       6 	
9    9	       7	
10  10	       6

Using Different Statistical Distributions to Generate Random Numbers in SAS

We can use the SAS rand() function to generate random numbers from different statistical distributions.

For example, if we want to generate normally distributed random numbers, we just pass “Normal” to rand()

rand_norm = rand("Normal");

You can change the mean and standard deviation by passing arguments specifying these properties:

// Normal distribution with mean 0 and standard deviation 1
rand_norm = rand("Normal", 0, 1);

You can see all of the different statistical distributions you can use “>here.

Hopefully this article has been useful for you to understand how you can generate random numbers using the SAS rand() function in your SAS code.