How can you check for unique values in a dataset in SAS?

Using PROC FREQ is a reliable method to check for unique values in a dataset. This procedure generates frequency counts for each distinct value of a specified variable, allowing you to see not only the unique values but also how many times each value appears in the dataset. When you examine the output of PROC FREQ, any value that appears only once can be identified easily, directly indicating which values are unique.

The UNIQUE function is not primarily designed for identifying unique values in a dataset context. It is a more general function used to evaluate whether the values in a list are unique and does not produce a comprehensive frequency distribution.

Creating a custom FORMAT does not inherently check for uniqueness; rather, it alters how data is displayed. While it might assist with formatting distinct values once identified, it doesn't provide a method to discover unique entries within the dataset directly.

Using the DISTINCT keyword is specific to SQL queries within SAS for selecting unique records from a database; however, it does not apply directly to data steps or PROC steps used in traditional SAS procedures like PROC FREQ. Thus, when interested in assessing unique values in a dataset broadly, PROC FREQ is the most straightforward and effective method.