Getting Started

 
All of these models were built using Microsoft Excel, and have been tested using the 2007, 2003 and 2002 releases (for Windows). They should also be compatible with earlier/later releases, but this hasn't been verified. Most of the models should also work in Excel 2008 for Mac. To use the models you will need to have a licensed copy of Excel installed. For some of the general equilibrium models you will need to have the Solver add-in installed (click here to view instructions). For others, macros must also be enabled for full functionality (click here to view instructions), although it is possible to use the models without enabling macros for most purposes (in the same way as the other Solver models). Macro functionality is not available on the Mac. 'Live' general equilibrium models and all partial equilibrium models do not require any special add-ins or macros.
 
Each Excel model is available from the download link on its description page. The models are arranged in the order that they would be encountered in a typical field course on international trade, starting with the positive theory of trade and then shifting to the theory of commercial policy. A topic index indicates suggested exercises and includes a listing by model. All the models have been been built with very similar interfaces, and they all work in a similar way. To use a model:
  • Go to the relevant page and retrieve the download. We recommend downloading the file to your computer and then opening in Excel - the browser interface to Excel does not support add-ins.
  • If necessary, install the Solver add-in and/or enable macros.
  • Open the sheet, allowing macros if required. In general any white cell is an exogenous variable or parameter that can be changed directly, and any colored cell (usually blue or grey) is an endogenous variable that reflects the solution value. For partial equilibrium and 'live' general equilibrium models you can change any exogenous value and the solution will automatically change to reflect the shock. In many cases spinners have been provided to allow shocks to be made smoothly by clicking up or down, otherwise an appropriate value can be typed in the box. For models using Solver, the solution will not update until you launch Solver. If macro has been provided, this is a matter of clicking the Solve model button on the sheet. It there is no macro (or if you have chosen not to enable it), then Solver can be launched by going to the Tools menu, selecting Solver, and clicking the Solve button in the dialog (in Excel 2003 or earlier) or pressing the Solver button under the Data tab on the ribbon, and clicking the Solve button in the dialog (in Excel 2007). A step-by-step example with the Solver version of the HOS model is shown here.
  • Observe the changes in the economic system numerically and geometrically.
More details can be found in the pages for each model, which also contain a graphical guide to the model components. Each page also suggests a series of topics that can be explored with the model, and in some cases sample assignments. The illustrated guides and sample exercises are replicated within each Excel sheet for easy access. If you are interested in how the models are built, a couple of simple examples that illustrate the principles involved can be found here. If you have further queries, please contact the authors.
 

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