|What are the models and why use them over commercial models?|
|The US Model
The United States model was developed by Ray Fair in 1974-1976, and it has been used since then for research, forecasting, policy analysis, and teaching. It has been available for use on personal computers since 1983 and was the first such model to be so. (And it was first on the Web!) The current version contains 26 stochastic equations and about 100 identities. The data base begins in the first quarter of 1952. The basic estimation technique is two-stage least squares. The model accounts for all flow-of-fund and balance-sheet constraints, which makes it useful for considering various monetary policy options. A complete description of the model is in Macroeconometric Modeling.
Each quarter the data base is updated, the model is reestimated, and a new forecast is made. The forecasts are not subjectively adjusted (no constant adjustments). The current estimation period is 1954:1-2014:3, and the current forecast period is 2014:4-2022:4.
The main strength of the US model is that it is probably the best approximation of the U.S. economy available. It has been extensively tested and analyzed, and unlike commercial models, it does not have to be subjectively adjusted to produce accurate forecasts. You can have more confidence using the model than using commercial models that the results are actually telling you something about how the macroeconomy works. Commercial models are not even consistently estimated, even though consistent techniques have been available for over 50 years, whereas the US model has been consistently estimated from its beginning. The past forecasting record of the model is updated each quarter, so the user always has a complete record of how the model has done. The four-quarter-ahead mean absolute error is currently 1.34 percentage points for the real GDP growth forecasts and 0.79 percentage points for the inflation forecasts (121 forecasts---the first one dated September 23, 1983). See The Forecasting Record of the US Model.
The MC Model