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SAS Functions [2-14]

SUM Functions

The SUM function allows you to add up values despite the present of missing values.

In SAS, there are two ways to add up numeric values: 

  1. Plus Sign (+) or
  2. SUM function

The usage of the Plus Sign (+) has been demonstrated in the previous session.
The downside of using the Plus Sign (+) is that the summation will not be performed with the present of missing values.

Let's illustrate this with an example.

The NUMBERS data set above contains 3 variables: Val0, Val1 and Val2. 

[Note: To see the NUMBERS data set on SAS Studio, run the code in the yellow box above]

Some values from the data set are clearly missing.

Now, we're going to add up all 3 variables using the Plus Sign (+). 

Example

Data Math1;
    Set Numbers;
    val3 = val0+val1+val2;
Run;

The numbers were not added up when there are missing values!

This is not good, as you could potentially lose tons of data because of the present of just 1 missing value!

The better way to add up values is to use the SUM function.

Example

Data Math2;
    Set Numbers;
    Val3 = Sum(of val0, val1, val2);
Run;

The SUM function will ignore any missing values when adding up the numbers.

No data will be lost due to missing values.


Function Structure

The SUM function is structured as:

Sum(of val1, val2, ...);

You can have as many parameters in the SUM function as you want.
Exercise

Copy and run the SALES data set from the yellow box below.

SALES contains 6 variables:
  • STOREID
  • MON: SALES (Monday)
  • TUE: SALES (Tuesday)
  • WED: SALES (Wednesday)
  • THR: SALES (Thursday)
  • FRI: SALES (Friday)


Write a SAS program to calculate the total sales of the week. Create any data set or variables if necessary.
Need some help? 


HINT:
The plus sign (+) will not work when there is missing value.


SOLUTION:
Data Sales_Week;
Set Sales;
Total = Sum(of Mon, Tue, Wed, Thr, Fri);
Run;

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