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Autobox Modeling Description
Autobox handles a single endogenous equation
incorporating either pre-identified causal series or empirically
identified dummy series, which are found to be statistically
significant. The set of pre-identified series can be either stochastic
or deterministic (dummy) in form. In its search for the most
appropriate model form and the optimal set of parameters the final
model can either be:
- Purely empirical
- A starting model could be used.
A final model may require one or more of the following structures:
- Power transforms like Log, Square Root and Reciprocal etc.
- Variance stabilization due to deterministic changes in the background error variance.
- Data segmentation or splitting as evidenced by a statistically significant change in either model form or parameters.
Enroute to its tour de
force Autobox will evaluate numerous possible models/parameters that
have been suggested by the data itself. In practice, a realistic limit
is set on the maximum number of model form iterations. The exact
specifics of each tentative model is not pre-set thus the power of
Autobox emerges. The kind and form of the tentative models may never
before have been tried. Each dataset speaks for itself and suggests the
iterative process.
The Final Model could be as simple as:
- A simple trend model or a simple ordinary least squares model.
- An exponential smoothing model.
- A simple weighted average where the weights are either equal or unequal.
- A Cochrane-Orcutt or ordinary least squares with a first order fixup.
- A simple ordinary least squares model in differences containing some needed lags.
- A spline-like set of local trends superimposed with an arbitrary ARIMA model and perhaps a pulse or two.
The number of possible final models that Autobox could find is infinite
and only discoverable via a true expert system like Autobox. A final
model may require one or more of the following
Seasonal Structures:
- Seasonal ARIMA structure where the prediction depends on some previous
reading S periods ago.
- Seasonal structure via a complete set of seasonal dummies reflecting a fixed response based upon the particular period.
- Seasonal structure via a partial set of seasonal dummies reflecting a fixed response based upon the particular period.
The Final Model will satisfy both:
- Necessity tests that guarantee the estimated coefficient is statistically significant.
- Sufficiency tests that guarantee that the error process is:
- unpredictable on itself.
- not predictable from the set of causals.
- has a constant mean of zero.
The Final model will contain one or more of the following structures:
- CAUSAL with correct lead/lag specification.
- MEMORY with correct "autoregressive memory".
- DUMMY with correct pulses, level shifts or spline time trends
Typical Forecasts
- Daily Demand For Cash at an ATM Machine view graph
- Monthly New Prescriptions for Diabetes view graph
- Monthly Outbreak of Dengue Disease view graph
- Weekly Sales of General Mills Frozen Biscuits view graph
- Detecting a Lead Effect view graph
- Daily Beer Sales for one Store-SKU view graph
- Changing Times view graph
- More Changing Times view graph
- No Trend or Seasonality view graph
- No Memory ..Just a Level Shift view graph
- Czech GDP reflects democratization view graph
© 1999-2009 Automatic Forecasting Systems Inc.


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