What does the NMISS option do in a SAS procedure?

The option NMISS in a SAS procedure specifically serves the purpose of displaying the number of observations that contain missing values for a variable or a set of variables being analyzed. When invoking procedures that can utilize this option, such as PROC MEANS or PROC FREQ, NMISS will tally and present how many of the analyzed observations are incomplete due to missing values. This is particularly useful in understanding the extent of missing data in the dataset, which is a critical aspect of data analysis and quality assessment.

Choosing this option helps statisticians and data analysts to gauge the reliability and completeness of the dataset they are working with. Other related options in SAS provide alternative functions like counting all observations or removing missing values, but NMISS specifically focuses on identifying and counting those with missing data. This targeted approach enhances the ability to make informed decisions about data cleaning and analysis strategies.