The Statistical Analysis System (SAS) is a powerful software suite used for data management, statistical analysis, and reporting. A crucial aspect of working with dates in SAS is understanding SAS date formats. SAS stores dates as the number of days since January 1, 1960, but these dates must often be displayed in a readable format for reporting and analysis. This article explores various SAS date formats, how to apply them, and best practices for handling dates in SAS.

Understanding SAS Date Values

SAS date values are numeric and represent the number of days from January 1, 1960. For example:

• 0 represents January 1, 1960
• 1 represents January 2, 1960
• -1 represents December 31, 1959

Since SAS stores dates numerically, applying date formats is essential to present them in human-readable form.

Commonly Used SAS Date Formats

SAS provides multiple date formats that control how date values are displayed. Below are some of the most commonly used formats:

1. DATE Format

This format displays the date as ddmmmyyyy, where the month is abbreviated, such as 01JAN2024.

2. MMDDYY Format

This format displays dates in MM/DD/YYYY or MM-DD-YYYY style, such as 01/01/2024.

3. DDMMYY Format

This format displays dates in DD/MM/YYYY or DD-MM-YYYY style, such as 01/01/2024.

4. MONYY Format

Displays dates as MonYYYY, often used in financial reports, such as JAN2024.

5. WORDDATE Format

Converts dates into a more readable full-text format, such as January 1, 2024.

Customizing Date Formats in SAS

You can customize date formats in SAS using the PROC FORMAT procedure. This is useful when you need a unique display format for reporting, such as showing dates in the form 01-Jan-2024.

Applying Date Formats in a Dataset

You can apply date formats within datasets to ensure clarity in reports and analyses. Formatting helps display dates in a readable manner instead of showing raw numeric values.

Date Format vs. Date Informat

Date Formats

• Format: Controls how a date is displayed.
• Example: Displaying a date as 01JAN2024 instead of its numeric value.

Date Informats

• Informat: Controls how SAS reads date values from raw data.
• Example: Interpreting a date from input data and converting it into SAS date format.

Handling Date Ranges and Calculations

Since SAS stores dates as numeric values, you can perform calculations such as adding or subtracting days to determine future or past dates.

For example, adding 30 to a given date moves it 30 days forward, allowing for easy date-based computations.

Conclusion

Understanding SAS date formats is crucial for proper data presentation and analysis. SAS provides a variety of formats such as DATE9., MMDDYY10., DDMMYY10., and WORDDATE18. to suit different reporting needs. By applying the correct date format, you ensure that your reports are clear and easy to interpret. Whether you are formatting, reading, or calculating dates, mastering SAS date formats can significantly enhance your data analysis workflow.