The X12 Procedure
- Overview
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Getting Started
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Syntax
Functional Summary PROC X12 Statement ADJUST Statement ARIMA Statement AUTOMDL Statement BY Statement CHECK Statement ESTIMATE Statement EVENT Statement FORECAST Statement ID Statement IDENTIFY Statement INPUT Statement OUTLIER Statement OUTPUT Statement REGRESSION Statement TABLES Statement TRANSFORM Statement USERDEFINED Statement VAR Statement X11 Statement
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Details
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Examples
- References
| ADJUST Statement |
The ADJUST statement adjusts the series for leap year and length-of-period factors prior to estimating a regARIMA model. The "Prior Adjustment Factors" table is associated with the ADJUST statement.
The following option can appear in the ADJUST statement:
- PREDEFINED=LOM | LOQ | LPYEAR
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specifies length-of-month adjustment, length-of-quarter adjustment, or leap year adjustment. PREDEFINED=LOM and PREDEFINED=LOQ are equivalent because the actual adjustment is determined by the interval of the time series. Also, because leap year adjustment is a limited form of length-of-period adjustment, only one type of predefined adjustment can be specified. The PREDEFINED= option should not be used in conjunction with PREDEFINED=TD or PREDEFINED=TD1COEF in the REGRESSION statement or MODE=ADD or MODE=PSEUDOADD in the X11 statement. PREDEFINED=LPYEAR cannot be specified unless the series is log transformed.
If the series is to be transformed by using a Box-Cox or logistic transformation, the series is first adjusted according to the ADJUST statement, and then it is transformed.
In the case of a length-of-month adjustment for the series with observations
, each observation is first divided by the number of days in that month, 
, and then multiplied by the average length of month (30.4375), resulting in 
. Length-of-quarter adjustments are performed in a similar manner, resulting in 
, where 
is the length in days of quarter 
. Forecasts of the transformed and adjusted data are transformed and adjusted back to the original scale for output.