SAS/Ets User's Guide 107. Provides detailed reference material for using SAS/ETS software and guides you through the analysis and forecasting of features such as univariate and multivariate time series, cross-sectional time series, seasonal adjustments, multiequational nonlinear models, discrete choice models, limited dependent variable models, portfolio analysis, and generation of financial reports, with introductory and advanced examples for each procedure. You can also find complete information about two easy-to-use point-and-click applications: the Time Series Forecasting System, for automatic and interactive time series modeling and forecasting, and the Investment Analysis System, for time-value of money analysis of a variety of investments | 1052 F Chapter 18 The MODEL Procedure NAHEAD n specifies a simulation of n-period-ahead dynamic forecasting. The NAHEAD option is used to simulate the process of using the model to produce successive forecasts to a fixed forecast horizon in which each forecast uses the historical data available at the time the forecast is made. Note that NAHEAD 1 produces a static one-step-ahead solution. NAHEAD 2 produces a solution that uses one-step-ahead solutions for the first lag LAG1 functions return static predicted values and actual values for longer lags. NAHEAD 3 produces a solution that uses NAHEAD 2 solutions for the first lags NAHEAD 1 solutions for the second lags and actual values for longer lags. In general NAHEAD n solutions use NAHEAD n-1 solutions for LAG1 NAHEAD n-2 solutions for LAG2 and so forth. START s specifies static solutions until the 5th observation and then changes to dynamic solutions. If the START s option is specified the first observation in the range in which LAGn delivers solved predicted values is s n while LAGn returns actual values for earlier observations. STATIC specifies a static solution. In static solution mode actual values of the solved variables from the input data set are used by the lagging functions. Solution Mode Options Use of Available Data FORECAST specifies that the actual value of a solved variable is used as the solution value instead of the predicted value from the model equations whenever nonmissing data are available in the input data set. That is in FORECAST mode PROC MODEL solves only for those variables that are missing in the input data set. SIMULATE specifies that PROC MODEL always solves for all solution variables as a function of the input values of the other variables even when actual data for some of the solution variables are available in the input data set. SIMULATE is the default. Solution Mode Options Numerical Solution Method JACOBI computes a simultaneous solution using a Jacobi iteration. NEWTON computes a
