SAS 面试题与答案

Question: Explain the difference between CLASS and BY statements in PROC means.

Answer: The CLASS statement in PROC MEANS is used to specify categorical variables for subgroup analysis, while the BY statement is used for creating separate summary statistics for different levels of a variable.

Example:

PROC MEANS DATA=dataset; VAR variable; CLASS category_variable; RUN; 
PROC MEANS DATA=dataset; VAR variable; BY grouping_variable; RUN;