The HPFENGINE Procedure
PROC HPFENGINE Statement
PROC HPFENGINE options;
The PROC HPFENGINE statement invokes the HPFENGINE procedure. You can specify the following options:
TASK= Option Details
This section describes the override-options that can be specified in any TASK=action context. Many of these settings are used only during the model selection phase of PROC HPFENGINE processing (that is, during the processing performed when you specify TASK=SELECT). However, there can be a need for them in any TASK=action context. PROC HPFENGINE can generate special placeholder forecasts for some of the time series it encounters during a TASK=SELECT run. These are generally the result of nominal data that prohibits PROC HPFENGINE from performing an evaluation of the model selection list for the series. As such, these forecasts represent excepted cases. Many of these cases are triggered from various override-options in effect during the TASK=SELECT run. For example, if you specified TASK=SELECT(MINOBS=6), any series with fewer than six nonmissing observations would trigger a forecast using the _MEAN_ model. Another example would be the _ZERO_ model that arises from use of the ENDZEROS= option. PROC HPFENGINE recognizes these excepted cases when processing the information from its INEST= data set that is saved as the OUTEST= data set from a previous PROC HPFENGINE run. When recognized in this way, PROC HPFENGINE attempts to perform model selection processing on those excepted cases regardless of the TASK=action requested. To deal with any such cases properly and ensure consistent behavior, you should specify the same set of override-options for your PROC HPFENGINE runs without regard to the action value specified.
You can specify these override-options in the context of any admissible action for TASK=.
- ALPHA=number
-
specifies the significance level to use in computing the confidence limits of the forecast. The ALPHA= value must be between 0 and 1. For example, ALPHA=0.05 produces 95% confidence intervals.
If a selection list does not specify ALPHA and ALPHA is specified in TASK=, the value that is specified takes effect. If ALPHA is specified in the selection list, the corresponding value specified in TASK= is not used unless the OVERRIDE option is also present.
- CRITERION=option
-
specifies the model selection criterion (statistic of fit) to be used to select from several candidate models. The following list shows the valid values for the CRITERION=option and its corresponding statistic of fit:
- SSE
sum of square error
- MSE
mean square error
- RMSE
root mean squared error
- UMSE
unbiased mean squared error
- URMSE
unbiased root mean squared error
- MAXPE
maximum percent error
- MINPE
minimum percent error
- MPE
mean percent error
- MAPE
mean absolute percent error
- MDAPE
median absolute percent error
- GMAPE
geometric mean absolute percent error
- MINAPES
minimum absolute error percent of standard deviation
- MAXAPES
maximum absolute error percent of standard deviation
- MAPES
mean absolute error percent of standard deviation
- MDAPES
median absolute error percent of standard deviation
- GMAPES
geometric mean absolute error percent of standard deviation
- MINPPE
minimum predictive percent error
- MAXPPE
maximum predictive percent error
- MPPE
mean predictive percent error
- MAPPE
symmetric mean absolute predictive percent error
- MDAPPE
median absolute predictive percent error
- GMAPPE
geometric mean absolute predictive percent error
- MINSPE
minimum symmetric percent error
- MAXSPE
maximum symmetric percent error
- MSPE
mean symmetric percent error
- SMAPE
symmetric mean absolute percent error
- MDASPE
median absolute symmetric percent error
- GMASPE
geometric mean absolute symmetric percent error
- MINRE
minimum relative error
- MAXRE
maximum relative error
- MRE
mean relative error
- MRAE
mean relative absolute error
- MDRAE
median relative absolute error
- GMRAE
geometric mean relative absolute error
- MAXERR
maximum error
- MINERR
minimum error
- ME
mean error
- MAE
mean absolute error
- MASE
mean absolute scaled error
- RSQUARE
R square
- ADJRSQ
adjusted R square
- AADJRSQ
Amemiya’s adjusted R square
- RWRSQ
random walk R square
- AIC
Akaike information criterion
- AICC
finite sample corrected AIC
- SBC
Schwarz Bayesian information criterion
- APC
Amemiya’s prediction criterion
- ENDZEROS=(MAXNUM=number MAXPCT=percent MINOBS=number)
-
specifies criteria that control the use of a _ZERO_ model for a series. A _ZERO_ model is used when the number of trailing zero values in the series fails to indicate that a nonzero model is appropriate. (By default, no _ZERO_ model testing is performed.) If CHOOSE= is specified in the model selection list that is used for a series, these options have no effect and the chosen model is used.
You can specify the following suboptions:
- MAXNUM=number
specifies the count of trailing zero values needed in order to consider a nonzero model. If the series has number or fewer trailing zero observations, then a nonzero model is considered. For example, if you specify ENDZEROS=(MAXNUM=10), then a nonzero model is considered only if the series has 10 or fewer trailing zero values.
- MAXPCT=P
specifies the maximum percentage of trailing zero values relative to the number of nonzero values in the entire series. If the number of trailing zero observations in the series is fewer than or equal to P% of the nonmissing and nonzero values of the entire series, then a nonzero model is considered. The value of P is in the range (0,100). If you specify ENDZEROS=(MAXPCT=20), then a nonzero model is considered only if the number of trailing zero values is fewer than or equal to 20% of the number of nonmissing and nonzero values of the entire series.
- MINOBS=number
specifies the minimum series length that is required to perform the _ZERO_ model test. For example, if you specify MINOBS=8, then the _ZERO_ model test is not performed on any series whose length is fewer than eight observations. By default, MINOBS=0, which implies no minimum length exclusion.
If MAXNUM=0 and MAXPCT=100 or MAXPCT=0, then a nonzero model is always considered. You can specify a combination of the MAXNUM= and MAXPCT= options. If you specify ENDZEROS=(MAXNUM=10 MAXPCT=20), then a nonzero model is considered only if the series has 10 or fewer trailing zero values and if the number of trailing zero values is fewer than or equal to 20% of the number of nonmissing and nonzero values of the entire series.
When a series fails to use a nonzero model by the criteria specified in this option, the _ZERO_ model is used. In the OUTEST= data set, the _MODEL_ variable is set to _ZERO_, and the remaining data set variables that are associated with the parameter estimates are set to missing.
- HOLDOUT=n
specifies the size of the holdout sample to be used for model selection. The holdout sample is a subset of actual time series that ends at the last nonmissing observation.
- HOLDOUTPCT=number
specifies the size of the holdout sample as a percentage of the length of the time series. If HOLDOUT=5 and HOLDOUTPCT=10, the size of the holdout sample is
, where T is the length of the time series with beginning and ending missing values removed.
- INTERMITTENT=number
specifies a number greater than 1 that is used to determine whether or not a time series is intermittent. If the median demand interval is equal to or greater than this number, then the series is assumed to be intermittent.
- MINOBS=(TREND=n )
-
specifies that no trend model be fit to any series with fewer than n nonmissing values. Normally the models in a selection list are not subset by trend.
Incorporation of a trend is checked only for smoothing, UCM, and ARIMA models. For the smoothing case, only simple smoothing is a non-trend model. For UCM, the absence of a slope component qualifies it as a non-trend model. For ARIMA, there must be no differencing of the dependent variable for PROC HPFENGINE to consider it a non-trend model.
The value of n must be greater than or equal to 1. The default is TREND=1.
- MINOBS=(SEASON=n )
specifies that no seasonal model be fit to any series with fewer observations than n multiplied by the seasonal cycle length. The value of n must be greater than or equal to 1. The default is SEASON=2.
- MINOBS=n
specifies that any series with fewer than n nonmissing values not be fit using the models in the selection list, but instead be forecast as the mean of the observations in the series. The forecast is recorded as using the _MEAN_ model in the OUTEST= data set _MODEL_ variable. The value of n must be greater than or equal to 1. The default is MINOBS=1.
- NOALTLIST
disables the default action and sets the forecast to missing if no models can be fit from the initial selection list. (By default, if none of the models in a selection list can be successfully fit to a series, PROC HPFENGINE returns to the selection list Sashelp.Hpfdflt.Best and restarts the selection process.) There will be an observation in OUTSUM=, if requested, that corresponds to the variable and BY group in question, and the _STATUS_ variable will be nonzero.
- OVERRIDE
forces the use of any options listed.
- SEASONTEST=option
-
specifies the options related to the seasonality test.
The following values for the SEASONTEST= option are allowed:
- NONE
no test
- (SIGLEVEL=number)
specifies the significance probability value to use in testing whether seasonality is present in the time series. The value must be between 0 and 1. A smaller value of the SIGLEVEL= option means that stronger evidence of a seasonal pattern in the data is required before PROC HPFENGINE uses seasonal models to forecast the time series.
The default is SEASONTEST=(SIGLEVEL=0.01).
The following details apply to the usage of SEASONTEST=(SIGLEVEL=number):
If the HPFDIAGNOSE procedure is used to identify a single model, and that model is input to the HPFENGINE procedure by using the REPOSITORY= option and the INEST= option, then SEASONTEST(SIGLEVEL=) does not apply. Note that the default SIGLEVEL= value for PROC HPFDIAGNOSE is 0.05.
If no model is specified for PROC HPFENGINE, then the procedure chooses a model from the list of default smoothing models. In this case, SEASONTEST(SIGLEVEL=) does apply, and SIGLEVEL=0.01 is the default value for choosing between a seasonal and nonseasonal model.
If a model that is included in the PROC HPFENGINE selection list is created using the METHOD=BEST option of the ESM statement in the HPFESMSPEC procedure, then the significance level for including seasonal components in the model is fixed at 0.05. The SEASONTEST(SIGLEVEL=) value in PROC HPFENGINE does not affect the identification of seasonal components in the BEST model when you use this method.