MACURVES Statement

The X11 Procedure

MACURVES Statement

MACURVES month=option ...;

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': specifies a three-term moving average for the month
'3X3': specifies a three-by-three moving average
'3X5': specifies a three-by-five moving average
'3X9': specifies a three-by-nine moving average
STABLE: 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 3x3 ( a three-term moving average of a three term moving average) for February, a 3x5 ( a three-term moving average of a five-term moving average) for March, and a 3x9 ( 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 U.S. Bureau of Census, 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.

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