About the GTAP Model
The materials in this course support the UNI-CGE model, a single-country computable general equilibrium model written in the GAMS modeling software. Some learners may want to use the GTAP CGE model in this course instead of the UNI-CGE model. The GTAP model is a global CGE model written in the GEMPACK software. The GTAP model was developed by the Center for Global Trade Analysis at Purdue University.
Comparing UNI-CGE and GTAP Models
The UNI and the GTAP models are both standard CGE models with many commonalities, but their underlying theories also differ in some respects. Table 1 provides a comparison of key features of the UNI and GTAP CGE models, The table can guide you in understanding which materials in this course can be used to learn about the GTAP CGE model.
| Item | UNI-CGE | GTAP |
|---|---|---|
| Data | SAMs and elasticities | SAMS and 6 elasticities |
| Demand | Cobb-Douglas, LES | Constant difference of elasticities |
| Supply | ||
| Factor substitution | CES substitution | CES substitution |
| Factor mobility | Sector specific/fully mobile | CET (ranges from sector-specific to fully mobile) |
| Factor unemployment | Factor closure - full employment or unemployment | Factor closure - full employment or unemployment |
| Intermediate demand | Leontief | CES substitution |
| Trade | ||
| Import demand | Armington aggregation | Armington aggregation |
| Export supply | CET export supply | Responds to foreign import demand |
| Macro closures | Investment-savings, government savings, foreign savings/trade balance | Investment-savings, foreign savings/trade balance |
Where to Get the GTAP Model
Learners can download the RunGTAP model from the GTAP Center by visiting the Center's website: www.gtap.org.
On the website, select Models/RunGTAP and follow instructions to download the RunGTAP model. The NUS333 database, identical to the US333 SAM used in this course, is included in the RunGTAP model.
Learn About the GTAP Model
The GTAP model has a user-friendly interface, "RunGTAP" that allows users to quickly master the use of the model, freeing students to focus on the economics of the model and the experiments. To learn more about the GTAP model, see The Standard GTAP Model, Version 7, by Corong et al., Journal of Global Economic Analysis, 2017. The book Introduction to CGE Models (Burfisher, 2021) might also be useful. It includes hands-on modeling exercises using the GTP model.