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: Percentage Change

Scenario Comparative Report

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)