How does the SORT procedure handle missing values?

The SORT procedure in SAS treats missing values as the smallest possible value. When data is sorted, missing values are placed before any other values. This behavior is consistent across various data types, including numeric and character data.

For numeric data, a missing value is treated as less than any non-missing numeric value, which explains why it appears at the beginning of a sorted list. In the case of character data, missing values are considered to be less than any character string in alphabetical order, similarly placing them first.

This treatment allows analysts to be aware of how missing data is positioned when examining sorted results, and is crucial for various data analysis tasks. Understanding this sorting behavior is important for anyone working with SAS data, as it can affect the outcomes of analyses and reports that consider the order of data values.