The EVENT statement specifies events to be included in the regression portion of the regARIMA model. Multiple EVENT statements can be specified. Dummy variable values for EVENT variables are generated by the X12 procedure, however, the EVENT variables are input as user-defined regression effects to the X-12-ARIMA method. Thus, the EVENT variables are treated in the same manner as it treats variables specified in the USERVAR= option in the REGRESSION statement. If a MDLINFOIN= data set is not specified in the PROC X12 statement, then all variables specified in the EVENT statements are applied to all BY groups and all time series that are processed. If a MDLINFOIN= data set is specified, then the EVENT statements apply only if no regression information for the BY group and series is available in the MDLINFOIN= data set. The events specified in the EVENT statements either must be SAS predefined events or must be defined in the data set specified in the INEVENT= option in the PROC X12 statement. For a summary of SAS predefined events, see the section SAS Predefined Events.
The EVENT statement can also be used to include outlier, level-shift, and temporary change regressors that are available as predefined U.S. Census Bureau variables in the X-12-ARIMA program. For example, the following statements specify an additive outlier in January 1970 and a level-shift that begins in July 1971:
proc x12 data=ICMETI seasons=12 start=jan1968; event AO01JAN1970D CBLS01JUL1971D;
The following statements specify an additive outlier in the second quarter 1970 and a temporary change that begins in the fourth quarter 1971:
proc x12 data=ICMETI seasons=4 start='1970q1'; event AO01APR1970D TC01OCT1971D;
The following options can appear in the EVENT statement: