PROC UNIVARIATE excludes missing values for an analysis variable before calculating statistics. Each analysis variable is treated individually; a missing value for an observation in one variable does not affect the calculations for other variables. The statements handle missing values as follows:

• If a BY or an ID variable value is missing, PROC UNIVARIATE treats it like any other BY or ID variable value. The missing values form a separate BY group.

• If the FREQ variable value is missing or nonpositive, PROC UNIVARIATE excludes the observation from the analysis.

• If the WEIGHT variable value is missing, PROC UNIVARIATE excludes the observation from the analysis.

PROC UNIVARIATE tabulates the number of missing values and reports this information in the ODS table named "Missing Values." See the section ODS Table Names. Before the number of missing values is tabulated, PROC UNIVARIATE excludes observations when either of the following conditions exist:

• you use the FREQ statement and the frequencies are nonpositive

• you use the WEIGHT statement and the weights are missing or nonpositive (you must specify the EXCLNPWGT option)