In PROC MEANS, what happens when the data set contains missing values?

In PROC MEANS, when calculating statistics such as mean, median, standard deviation, etc., missing values are excluded from these calculations. This behavior ensures that the results provided by the procedure reflect only the available (non-missing) data, leading to more accurate statistical summaries. For example, if you have a data set with some missing entries, PROC MEANS will only consider the observations with actual values when performing its calculations, which helps maintain the integrity of the analysis by providing valid results based on the existing data.

This functionality is particularly useful in real-world data analysis where missing values can be common. In contrast, if calculations included missing values, the results could be misleading or invalid. Other options suggesting that calculations include missing values, use only the last observation, or create an error are not aligned with the standard behavior of PROC MEANS in SAS.