Comparative Analysis
Multiple Submissions vs.
Loops
AGEC 641 Lab, Fall 2010
Mario Andres Fernandez
Based on material written by Gillig and McCarl; Improved upon by many previous
lab instructors.
Special thanks to Yuquan “Wolfgang” Zhang
Comparative Analysis
As is often (always) the case, one is interested to see outcomes
under different scenarios.
Two ways to conduct comparative analysis
 Use multiple GAMS submissions or multiple solves
generating report writing output and then manually
comparing the analysis results
 Use the GAMS LOOP procedure and set up a comparative
scenario analysis system that creates cross scenario
comparison tables
Example
Scenarios
What if one has a RAP (risk aversion parameter) of “1.5” or “5.0”?
Multiple GAMS Submissions
Report writing commands use values from the most recent
solution.
Multiple GAMS Submissions
Multiple GAMS Submissions
Multiple GAMS Submissions: Percentage Change
Scenario Comparative Report
Loop
Loop
Loop: Structural Modification
Increasing run efficiency using the Save and Restart procedure.
We can associate a set of execution time parameters with a file
Save work files: s = .\t\a1
Restart work files: r = .\t\a1
(1)
(2)