Handling Dates in SAS: A Comprehensive Guide

The SAS system provides a versatile method for working with dates and times, enabling users to process and manipulate date data efficiently. SAS handles dates as the number of elapsed days since January 1, 1960, which makes it easy to perform various operations and calculations.

Understanding SAS Date Storage

In the SAS environment, dates are stored as numeric variables. Specifically, the system interprets these variables in a unique way by representing them as the number of days that have elapsed since January 1, 1960. This baseline date is crucial for all date-related calculations within the SAS environment. For example, January 1, 1960, is stored as 0, which is the starting point for all subsequent dates. Conversely, December 30, 1959, is represented as -2, and December 31, 1960, is stored as 365.

Manipulating Dates in SAS

One of the most convenient features of the SAS date system is its ability to perform simple arithmetic operations on dates. For instance, if you want to determine the difference between two dates, you can subtract one SAS date from another to obtain the number of days between them. Adding to this, you can easily manipulate dates by adding or subtracting days, weeks, months, or even years. This functionality makes it straightforward to generate future or past dates, such as adding 7 to a SAS date to make the date exactly one week later.

Working with Times in SAS

While dates in SAS are stored as days since January 1, 1960, times are stored as the number of elapsed seconds since midnight. This allows for precise time tracking and arithmetic operations within the SAS environment. For example, if you need to perform time-based calculations, you can use elapsed seconds to manipulate time values effectively.

Useful Functions, Formats, and Informats

The SAS system includes a wide range of built-in functions, formats, and informats that facilitate further operations on dates and times. These tools are invaluable for various tasks, such as formatting date and time values according to specific requirements, converting string dates into SAS dates, or displaying dates in a human-readable format. The best resource for exploring these functions, formats, and informats is the official SAS documentation, which provides extensive guidance and examples.

Conclusion

With its robust system for handling dates and times, SAS offers a powerful and flexible framework for data processing and analysis. Understanding how dates and times are stored and manipulated in SAS is essential for any user looking to make the most of this system. By leveraging the arithmetic capabilities and built-in functions, you can easily calculate, format, and interpret date and time data, making your data analysis tasks more efficient and accurate.

References

You can find detailed information on how to work with dates and times in SAS by referring to the SAS documentation. This resource provides comprehensive guidance on the intricacies of date and time handling in SAS, helping you to fully leverage the system's capabilities.