sas datetime formats

Guri Bee

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18-10-2024

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Mastering SAS Datetime Formats: A Comprehensive Guide

SAS, a powerful statistical software, handles dates and times using a unique system of formats. Understanding these formats is crucial for accurately displaying, manipulating, and analyzing your data. This article will guide you through the intricacies of SAS datetime formats, providing practical examples and insights to enhance your data analysis skills.

Understanding the Basics

At its core, SAS stores dates as integers representing the number of days since January 1, 1960, while times are stored as fractions of a day. This system, while efficient, can be challenging to grasp initially.

Here's a breakdown:

• Date Format: SAS uses the DATE format to display dates in various styles (e.g., MMDDYY, YYMMDD). The DATE format itself doesn't affect the underlying data; it only alters the representation.
• Time Format: Similar to dates, SAS uses the TIME format to display times in various formats (e.g., HHMMSS, HH:MM:SS).
• Datetime Format: For combined date and time values, SAS uses the DATETIME format. This allows for flexible display options, such as MMDDYY HH:MM:SS.

Common SAS Datetime Formats

Here are some commonly used SAS datetime formats, along with their respective representations:

Note: Formats like DATE9. and DATE7. are widely used because they are easy to read and process. However, other formats like DATETIME16. and DATETIME18. provide greater flexibility and can be used depending on your specific requirements.

Practical Examples

Let's illustrate how to use these formats with some real-world scenarios:

1. Converting a Character String to a Date:

data mydata;
   input date_char $;
   date_num = input(date_char, date9.);
   format date_num date9.;
   put date_num;
run;

In this example, we read a character string (date_char) representing a date in MMDDYY format and convert it to a numeric date (date_num) using the input function with the date9. format. We then display the date in MMDDYY format using the format statement.

2. Extracting Time from a Datetime Variable:

data mydata;
   input datetime_var datetime16.;
   time_var = time(datetime_var);
   format time_var time8.;
   put time_var;
run;

Here, we extract the time component from a DATETIME variable (datetime_var) using the time function. We then format the extracted time using time8., displaying it as HH:MM:SS.

Mastering SAS Datetime Formats: Key Takeaways

1. Understanding how SAS stores dates and times as numeric values is fundamental.
2. Utilize appropriate format statements to display your data clearly and effectively.
3. Use the input function to convert character strings to dates and times.
4. Employ the time function to extract time components from datetime variables.

Pro Tip: For more in-depth information and advanced usage of SAS datetime formats, refer to the official SAS documentation. (https://support.sas.com/documentation/cdl/en/lrdict/65148/HTML/default/viewer.htm#n1ywx0y8h0g7j1p1g0h970r6s.htm)

By incorporating these techniques and leveraging the power of SAS datetime formats, you can enhance your data analysis capabilities, gaining valuable insights from your data and making informed decisions.