Analytical Engine's Demand planning(DP) mode run comprises of Prepossessing stage, followed by model application & testing stage. In Promotion Effectiveness(PE) mode run of engine, various promotional CFs are prepared and used before Forecast phase starts.
Forecast Phase of Engine Run:
Pre-processing Stage:
1. Treatment of missing values.
2. Detection of intermittency.
3. Preliminary outlier and regime change detection.
4. Removal of obvious (gross) outliers.
5. Data transformation for use in specific models.
Model application & Testing Stage:
1. Checking that the number of data points exceeds at least by two the number of causal factors. This is done to ensure that, No over-fitting occurs and coefficients for all causal factors can be determined.
2. Estimation. Statistical algorithms, are implemented to data and their parameters are calculated.
3. Fit and Residuals calculation. Fit is calculated by applying an estimated model to the historical period. It reflects the ability of the model to reproduce the actual series. The deviation of fit from the actual forms the residual series. The variance of residual, along with complexity (number of estimated parameters) is utilized to compute the weights for model averaging.
4. To check the ability of a model to mimic the actual series, a Fit validation is performed, provided the nableFitValidation flag is on.In Fit validation the residuals undergo a battery of statistical tests.Forecast performs identical calculation to Fit, only for the future period, lead.
5. To perform Forecast validation, both the parameter EnableForecastValidation and the variable ValidFit have to be “True”. This is because if a model reached this stage with invalid fit, it must be running at the highest forecast level, and at this level forecast validation is disabled, allowing a somewhat more liberal treatment of models. In Forecast validation models undergo three tests:
• A test for an unusual zigzag-type jump
more details on Demantra's Engine can be found in Oracle Metalink's Documentation library for Demantra.