The "Large" Model
J.F. Francois, Tinbergen Institute and CEPR |
|
© J.F. Francois, 1998-2002 |
The examples involving the "large"
model are based on the static, constant returns version of a multi-region
general equilibrium model developed by Joseph Francois and Bradley McDonald
(with critical help from Thomas Rutherford). This model, which is implemented
in GAMS/MPSGE, is the "vanilla" version of the model employed for
various Francois, McDonald and Nordstrom papers (1993, 1994, 1995, 1996 etc.)
on the Uruguay Round. The SAM included with this file was used for the 1995
World Bank conference "The developing countries and the Uruguay Round."
(Hence the working MPSGE model name "IBRD...". Model files are found
in the subdirectory "large" on the CD-ROM in the "course"
directory, and installed under the "course" directory on the c: drive
if the course material has been installed from the CD-ROM.
Social accounting data are benchmarked to 1992, and the sources are described
in the Francois, McDonald, and Nordstrom contribution to "The Uruguay
Round and the Developing Countries," World Bank discussion paper 304, 1995
(edited by Martin and Winters).
Model Regions and Sectors
regions |
production |
||
label |
region |
label |
sector |
AUSTNZ |
Australia and New Zealand |
GRAINS |
grains |
Viewing social accounting data: The social accounting data are contained in the flat text file SAM.INC.
The Model
This version of the model is the reference
model from which alternative extensions related to capital accumulation and
imperfect competition were compared. The version presented here illustrates a
variety of theoretical and practical issues:
Running the model: The model can be run immediately from the files in the "Large" directory by typing the following command at the DOS prompt or by executing it from the Windows Explorer.
EXP%.BAT
where
EXP1.BAT |
is the static Uruguay Roud experiment |
EXP2.BAT |
is a free trade in textile and clothing experiment |
EXP3.BAT |
provides a Solow steady-state version of EXP1 |
You can turn on simple dynamic features, involving Solow type savings
behaviour, through the variable "switch," which then needs to be set
equal to one. The model then involves comparison of counterfacutal
steady-states.
NOTE: The model may terminate with a
nonfatal error at the end. This involves division by zero when calculating
percentage changes in trade flows. It can be ignored.
The model requires GAMS, with an installed MCP solver (MILES or PATH). While a student/demonstration version is distributed (with permission) on the course CD, this is not sufficient to run this model. You will need a full GAMS license.
Once you have run the model, you can view the resuls of Experiment % by using Excel to import the file EXP%PRN. An example is presented below: Longer output files are contained in the list file EXP%.LST.
Note: The most recent version of GAMS comes with a graphical interface: GAMSIDE. You may want to explore using its utilities instead.
Some Technical notes and documentation
This model implements explicit quotas in MPSGE. This is a significant departure
from the representation of quantitative restraints as tax equivalents:
This model also uses MPSGE side constraints to endogenize the capital stock (involving steady-state closures).
CGE modelling in GAMS/MPSGE is explained in the following:
[1] T.
Rutherford (1998). "Economic Equilibirum Modelling with GAMS: An
Introduction to GAMS/MCP and GAMS/MPSGE" University of Colorado, June.
LARGE DIRECTORY FILES |
|
exp#.bat |
executable for experiment # |
exp#.gms |
the experiment # itself |
IBRD.gen |
A GAMS/MPSGE work file |
Miles.* |
solver option files |
par.inc |
the elasticities |
Readme.1st |
Text file for DOS-based model sessions |
Results.xls |
the contents of the exp#.prn files in a spreadsheet |
sam.inc |
the social accounting data |
tax.inc |
the tax data |
TheModel.gms |
MPSGE code for the model |
Wrtprm.gms |
Gams output utility |
Wrtprn.gms |
Gams ouptut utility |
Wrtset.gms |
Gams output utility |
NOTE: each model produces a tab and space delimited file that can be read by excel, with the name exp#.prn