Understanding the Differences between the SUM Function and ' ' Operator in SAS

SAS, a versatile programming language, offers several ways to perform arithmetic operations, including the SUM function and the ' ' operator for addition. While both functions are used for adding numeric values or variables, they have distinct differences in usage, handling missing values, and performance considerations. This article will explore these differences to help SAS programmers make informed decisions about when to use one or the other.

Basic Usage

Sum Function: The SUM function is a built-in function designed for adding multiple numeric arguments. It is particularly handy for summing more than two numbers without needing to repeat the operator. For example, you can use it to add up multiple variables like:

result SUM(a, b, c);

' ' Operator: The ' ' operator is used for simple arithmetic addition between two or more numeric values or variables. For straightforward addition, it can be as simple as:

result a b;

However, it requires explicit repetition when adding more than two numbers:

result a b c d;

Handling Missing Values

Sum Function: The SUM function treats missing values (indicated by a period, ., in SAS) as zero. Therefore, if any of the arguments are missing, it will not affect the sum. Here is an example:

data example; a 10; b .; /* missing value */ c 5; result SUM(a, b, c); /* result will be 15 */ run;

' ' Operator: On the other hand, if any operand in the ' ' operator is missing, the result will also be missing. This can be demonstrated by:

data example; a 10; b .; /* missing value */ c 5; result a b c; /* result will be . (missing value) */ run;

Multiple Arguments

Sum Function: The SUM function can handle multiple arguments in a clean and concise manner. It is particularly useful when summing a large number of variables. For example:

data example; a 10; b 5; c 20; d 15; result SUM(a, b, c, d); /* result will be 50 */ run;

' ' Operator: When using the ' ' operator, you need to repeat the operator for each variable. This can make the code less readable and more prone to errors when summing a large number of variables.

Performance Considerations

Sum Function: The SUM function is generally more efficient and cleaner when summing a large number of variables. Its ability to handle multiple arguments in a single statement reduces the need for repetitive code, which can significantly improve the performance and readability of the program.

' ' Operator: While the ' ' operator is straightforward for simple additions, it may not be as efficient when dealing with a large number of variables. This is mainly due to the need for repetitive and explicit operators, which can slow down the execution and increase the likelihood of syntax errors.

Example to Illustrate the Differences

Here is an example to illustrate the differences between the SUM function and the ' ' operator:

data example; a 10; b .; /* missing value */ c 5; /* Using operator */ result1 a b c; /* result1 will be . */ /* Using SUM function */ result2 SUM(a, b, c); /* result2 will be 15 */ /* Print results */ put result1 result2; run;

Summary

The SUM function is the preferred choice when you need to add multiple values and handle missing values gracefully. It is versatile and can efficiently handle a large number of variables without the need for repetitive operators.

On the other hand, the ' ' operator is suitable for straightforward addition when you are certain all operands are non-missing and you only have a few variables to add.

Always consider the specifics of your SAS program and the nature of the data you are working with to choose the most appropriate method for addition.