Modeling and Multivariate Methods - SAS

Chapter 14 Performing Time Series Analysis 361
Modeling Reports
Simulate Once provides one simulation of the model out k time periods. The simulation is shown on the
Model Comparison time series plot. To change k, use the Number of Forecast Periods option on the
platform red-triangle menu.
Simulate More provides the specified number of simulations of the model out k time periods. The
simulations are shown on the Model Comparison time series plot. To change k, use the Number of
Forecast Periods option on the platform red-triangle menu.
Remove Model Simulation
removes the simulations for the given model.
Remove All Simulation
removes the simulations for all models.
Generate Simulation generates simulations for the given model, and stores the results in a data table.
You specify the random seed, number of simulations, and the number of forecast periods.
Set Seed is used to specify the seed for generating the next forecasts.
The Model Comparison report provides plots for a model when the Graph checkbox is selected. Figure 14.7
shows the plots for the ARIMA(1,1,1) model.
Figure 14.7 Model Plots
The top plot is a time series plot of the data, forecasts, and confidence limits. Below that are plots of the
autocorrelation and partial autocorrelation functions.
Model Summary Table
Each model fit generates a Model Summary table, which summarizes the statistics of the fit. In the formulae
below, n is the length of the series and k is the number of fitted parameters in the model.
DF is the number of degrees of freedom in the fit, n – k.