What is the role of the BY statement in PROC MEANS?

The role of the BY statement in PROC MEANS is to create separate summaries for each group defined by the BY variables. When you use the BY statement, PROC MEANS processes the data for each unique combination of values in the specified BY variables, producing independent summary statistics for each group. This allows you to analyze how statistics like mean, median, or standard deviation vary across different categories within your dataset.

For instance, if you had a dataset with sales data segmented by region and you wanted to calculate the average sales for each region, using the BY statement with the region variable would yield distinct summaries for each region in your analysis.

The other choices do not accurately describe the function of the BY statement. Ordering results alphabetically is not the purpose of the BY statement but could be an outcome of how the data is structured. Filtering specific data points is generally managed using the WHERE statement, not BY. While you do specify the variables for analysis, the BY statement specifically relates to grouping and does not inherently determine which metrics are calculated.