X11 Statement

The X12 Procedure

X11 Statement

X11 options;

The X11 statement is an optional statement for invoking seasonal adjustment by an enhanced version of the methodology of the Census Bureau X-11 and X-11Q programs. You can control the type of seasonal adjustment decomposition calculated with the MODE= option. The output includes the final tables and diagnostics for the X-11 seasonal adjustment method listed in Table 6.3.

Table 6.3: Tables Related to X11 Seasonal Adjustment

Table Name	Description
B1	original series, adjusted for prior effects and forecast extended
C17	final weights for the irregular component
D8	final unmodified SI ratios (differences)
D8A	F tests for stable and moving seasonality, D8
D9	final replacement values for extreme SI ratios (differences), D iteration
D9A	moving seasonality ratios for each period
D10	final seasonal factors
D10D	final seasonal difference
D11	final seasonally adjusted series
D12	final trend-cycle
D13	final irregular component
D16	combined seasonal and trading day factors
D16B	final adjustment differences
D18	combined calendar adjustment factors
E4	ratio of yearly totals of original and seasonally adjusted series
E5	percent changes (differences) in original series
E6	percent changes (differences) in seasonally adjusted series
E7	percent changes (differences) in final trend component series
F2A - F2I	X11 diagnostic summary
F3	monitoring and quality assessment statistics
F4	day of the week trading day component factors
G	spectral plots

For more details on the X-11 seasonal adjustment diagnostics, refer to Shiskin, Young, and Musgrave (1967), Lothian and Morry (1978), and Ladiray and Quenneville (1999).

The following options can appear in the X11 statement.

MODE= ADD

MODE= MULT

MODE= LOGADD

MODE= PSEUDOADD

determines the mode of the seasonal adjustment decomposition to be performed. There are four choices: multiplicative (MODE=MULT), additive (MODE=ADD), pseudo-additive (MODE=PSEUDOADD), and log-additive (MODE=LOGADD) decomposition. If this option is omitted, the procedure performs multiplicative adjustments. Table 6.4 shows the values of the MODE= option and the corresponding models for the original (O) and the seasonally adjusted (SA) series.

Table 6.4: Modes of Seasonal Adjustment and Their Models

Value of Mode Option	Name	Model for O	Model for SA
mult	Multiplicative	O = C ×S ×I	SA = C ×I
add	Additive	O = C + S + I	SA = C + I
pseudoadd	Pseudo-Additive	O = C ×[ S + I - 1 ]	SA = C ×I
logadd	Log-Additive	Log(O) = C + S + I	SA = exp(C + I)

OUTFCST

OUTFORECAST

determines if forecasts will be included in certain tables sent to the output data set. If OUTFORECAST is specified, then forecasted values will be included in the output data set for tables A6, A8, A16, B1, D10, and D16. The default is not to include forecasts.

SEASONALMA=S3X1

SEASONALMA=S3X3

SEASONALMA=S3X5

SEASONALMA=S3X9

SEASONALMA=S3X15

SEASONALMA=STABLE

SEASONALMA=X11DEFAULT

SEASONALMA=MSR

specifies which seasonal moving average (also called seasonal "filter") will be used to estimate the seasonal factors. These seasonal moving averages are n ×m moving averages, meaning that an n-term simple average is taken of a sequence of consecutive m-term simple averages. X11DEFAULT is the method used by the U.S. Census Bureau's X-11-ARIMA program. The default for PROC X12 is SEASONALMA=MSR, which is the methodology of Statistic Canada's X-11-ARIMA/88 program.

The following seasonal filters can be selected for the entire series:

Table 6.5: X-12-ARIMA Seasonal Filter Options and Descriptions

Filter Name	Description of Filter
S3X1	A 3 ×1 moving average.
S3X3	A 3 ×3 moving average.
S3X5	A 3 ×5 moving average.
S3X9	A 3 ×9 moving average.
S3X15	A 3 ×15 moving average.
STABLE	Stable seasonal filter. As single seasonal factor for each
	calendar month or quarter is generated by calculating the simple
	average of all the values for each month or quarter (taken after
	detrending and outlier adjustment).
X11DEFAULT	A 3 ×3 moving average is used to calculate the
	initial seasonal factors in each iteration, and a 3 ×5 moving
	average to calculate the final seasonal factors.
MSR	Choose filter automatically using moving seasonality ratio of
	X-11-ARIMA/88 (Dagum 1988).

TRENDMA= value

specifies which Henderson moving average will be used to estimate the final trend-cycle. Any odd number greater than one and less than or equal to 101 can be specified. Example: trendma=23. If no selection is made the program will select a trend moving average based on statistical characteristics of the data. For monthly series, either a 9-, 13-, or 23-term Henderson moving average will be selected. For quarterly series, the program will choose either a 5- or a 7-term Henderson moving average.

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