How can statistics be summarized by groups in SAS?

The correct approach to summarizing statistics by groups in SAS is through the use of the CLASS statement in procedures such as PROC MEANS or PROC FREQ. The CLASS statement allows the user to specify the categorical variables that define the groups. Once these groups are established, SAS calculates summary statistics (like mean, count, or frequency) separately for each group defined by the CLASS variables.

For instance, if you have a dataset that includes sales data categorized by region, the CLASS statement enables you to generate summary statistics for each region, allowing for insights into performance that takes into account these groupings. This method is efficient and widely used in SAS analytics for group-based data analysis.

The other methods do not provide the same functionality for summarizing statistics by groups. The summary function in PROC DATA is not a common or valid method in SAS for statistical summarization. The GROUP option in DATA steps does not exist in this context for aggregation purposes as required here. Finally, while creating separate datasets for each group is theoretically possible, it is inefficient and unnecessary when PROC MEANS or PROC FREQ can handle the group summarization in a single step. Hence, using the CLASS statement is both the most effective and concise method for this task.