The X12 Procedure |
PROC X12 Statement |
The PROC X12 statement provides information about the time series to be processed by PROC X12. Either the START= or the DATE= option must be specified.
The original series is displayed in Table A1. If there are missing values in the original series and a regARIMA model is specified or automatically selected, then Table MV1 is displayed. Table MV1 contains the original series with missing values replaced by the predicted values from the fitted model. Table B1 is displayed when the original data is altered (for example, through an ARIMA model estimation, prior adjustment factors, or regression) or the series is extended with forecasts.
Although the X-12-ARIMA method handles missing values, there are some restrictions. In order for PROC X12 to process the series, no month or quarter can contain missing values for all years. For instance, if the third quarter contained only missing values for all years, then processing is skipped for that series. In addition, if more than half the values for a month or a quarter are missing, then a warning message is displayed in the log file, and other errors might occur later in processing. If a series contains many missing values, other methods of missing value replacement should be considered prior to seasonally adjusting the series.
The following options can appear in the PROC X12 statement.
specifies the input SAS data set used. If this option is omitted, the most recently created SAS data set is used.
specifies a variable that gives the date for each observation. Unless specified in the SPAN= option, the starting and ending dates are obtained from the first and last values of the DATE= variable, which must contain SAS date or datetime values. The procedure checks values of the DATE= variable to ensure that the input observations are sequenced correctly in ascending order. If the INTERVAL= option or the SEASONS= option is specified, the values of the date variable must be consistent with the specified seasonality or interval. If neither the INTERVAL= option nor the SEASONS= option is specified, then the procedure tries to determine the type of data from the values of the date variable. This variable is automatically added to the OUT= data set if a data set is requested in an OUTPUT statement, and the date values for the variable are extrapolated if necessary. If the DATE= option is not specified, the START= option must be specified.
specifies the date of the first observation. Unless the SPAN= option is used, the starting and ending dates are the dates of the first and last observations, respectively. Either this option or the DATE= option is required. When using this option, use either the INTERVAL= option or the SEASONS= option to specify monthly or quarterly data. If neither the INTERVAL= option nor the SEASONS= option is present, monthly data are assumed. Note that for a quarterly date, the specification must be enclosed in quotes. A four-digit year can be specified; if a two-digit year is specified, the value specified in the YEARCUTOFF= SAS system option applies. When using the START= option with BY processing, the start date is applied to the first observation in each BY group.
specifies the dates of the first and last observations to define a subset for processing. A single date in parentheses is interpreted to be the starting date of the subset. To specify only the ending date, use SPAN=(,mmmyy). If the starting or ending date is omitted, then the first or last date, respectively, of the input data set is assumed. A four-digit year can be specified; if a two-digit year is specified, the value specified in the YEARCUTOFF= SAS system option applies.
specifies the frequency of the input time series. If the input data consist of quarterly observations, then INTERVAL=QTR should be used. If the input data consist of monthly observations, then INTERVAL=MONTH should be used. If the INTERVAL= option is not specified and SEASONS=4, then INTERVAL=QTR is assumed; likewise, SEASONS=12 implies INTERVAL=MONTH. If both the INTERVAL= option and the SEASONS= option are specified, the values should not be conflicting. If neither the INTERVAL= option nor the SEASONS= option is specified and the START= option is specified, then the data are assumed to be monthly. If a date variable is specified using the DATE= option, it is not necessary to specify the INTERVAL= option or the SEASONS= option; however, if specified, the values of the INTERVAL= option or the SEASONS= option should not be in conflict with the values of the date variable. See Chapter 4, Date Intervals, Formats, and Functions, for more details about intervals.
specifies the number of observations in a seasonal cycle. If the SEASONS= option is not specified and INTERVAL=QTR, then SEASONS=4 is assumed. If the SEASONS= option is not specified and INTERVAL=MONTH, then SEASONS=12 is assumed. If the SEASONS= option is specified, its value should not conflict with the values of the INTERVAL= option or the values of the date variable. See the preceding descriptions for the START=, DATE=, and INTERVAL= options for more details.
suppresses the default, by which leading and trailing missing values are trimmed from the series. If NOTRIMMISS is used, PROC X12 automatically generates missing value regressors for any missing value within the span of the series, including leading and trailing missing values.
specifies the input data set that defines any user-defined event variables. This option can be omitted if events are not specified or if only SAS predefined events are specified in an EVENT statement. For more information about the format of this data set, see the section INEVENT= Data Set for details.
specifies an optional input data set that contains model information that can replace the information contained in the TRANSFORM, REGRESSION, ARIMA, and AUTOMDL statements. The MDLINFOIN= data set can contain BY-group and series names; it is useful for providing specific information about each series to be seasonally adjusted. See the section MDLINFOIN= and MDLINFOOUT= Data Sets for details.
specifies the optional output data set that contains the transformation, regression, and ARIMA information related to each seasonally adjusted series. The data set is sorted by the BY-group variables, if any, and by series names. The MDLINFOOUT= data set can be used as input for the MDLINFOIN= option. See the section MDLINFOIN= and MDLINFOOUT= Data Sets for details.
suppresses any printed output.
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