The MVPMONITOR Procedure
TIME variable ;
The TIME variable is a numeric variable that provides the chronological order or time values for measurements in a DATA=, HISTORY=, or TABLE= input data set. The values of the TIME variable are displayed on the horizontal axis of control charts. If no TIME statement is specified, the observation numbers from the input data set are displayed on the horizontal axis.
When there are multiple observations per time point in the data that are used to create the principal component model, the control limits for the SPE chart are computed differently; see the section Computing SPE Control Limits.