The X11 Procedure
- Overview
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Getting Started
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Syntax
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DetailsHistorical Development of X-11Implementation of the X-11 Seasonal Adjustment MethodComputational Details for Sliding Spans AnalysisData RequirementsMissing ValuesPrior Daily Weights and Trading-Day RegressionAdjustment for Prior FactorsThe YRAHEADOUT OptionEffect of Backcast and Forecast LengthDetails of Model SelectionOUT= Data SetThe OUTSPAN= Data SetOUTSTB= Data SetOUTTDR= Data SetPrinted OutputODS Table Names
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Examples
- References
The MACURVES statement specifies the length of the moving-average curves for estimating the seasonal factors for any month. This statement can be used only with monthly time series data.
The month=option specifications consist of the month name (or the first three letters of the month name), an equal sign, and one of the following option values:
- ’3’
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specifies a three-term moving average for the month
- ’3X3’
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specifies a three-by-three moving average
- ’3X5’
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specifies a three-by-five moving average
- ’3X9’
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specifies a three-by-nine moving average
- STABLE
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specifies a stable seasonal factor (average of all values for the month)
For example, the statement
macurves jan='3' feb='3x3' march='3x5' april='3x9';
uses a three-term moving average to estimate seasonal factors for January, a 
(a three-term moving average of a three-term moving average) for February, a 
(a three-term moving average of a five-term moving average) for March, and a 
(a three-term moving average of a nine-term moving average) for April.
The numeric values used for the weights of the various moving averages and a discussion of the derivation of these weights are given in Shiskin, Young, and Musgrave (1967). A general discussion of moving average weights is given in Dagum (1985).
If the specification for a month is omitted, the X11 procedure uses a three-by-three moving average for the first estimate of each iteration and a three-by-five average for the second estimate.