Using Time Intervals with SAS/ETS Procedures

Working with Time Series Data

Using Time Intervals with SAS/ETS Procedures

The ARIMA, FORECAST, and STATESPACE procedures use time intervals with the INTERVAL= option to specify the periodicity of the input data set. The EXPAND procedure uses time intervals with the FROM= and TO= options to specify the periodicity of the input and the output data sets. The DATASOURCE and CITIBASE procedures use the INTERVAL= option to control the periodicity of time series extracted from time series databases.

The INTERVAL= option (FROM= option for PROC EXPAND) is used with the ID statement to fully describe the observations that make up the time series. SAS/ETS procedures use the time interval specified by the INTERVAL= option and the ID variable in the following ways:

to validate the data periodicity. The ID variable is used to check the data and verify that successive observations have valid ID values corresponding to successive time intervals.
to check for gaps in the input observations. For example, if INTERVAL=MONTH and an input observation for January 1990 is followed by an observation for April 1990, there is a gap in the input data with two omitted observations.
to label forecast observations in the output data set. The values of the ID variable for the forecast observations after the end of the input data set are extrapolated according to the frequency specifications of the INTERVAL= option.

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