In the days before computers, accountants spread large sheets of paper out on their desks when it came time to update the financial status of their company. This was a task ideally suited for microcomputers and "electronic spreadsheets." Today, spreadsheet programs like Lotus 1-2-3 or Microsoft Excel are in wide use. Their prevalence raises important questions for system dynamics:

Can we build system dynamics models in spreadsheets?

And if we can,

Shouldn't we do so?

Using spreadsheets would certainly eliminate the need to explain the "stock and flow" concepts. Perhaps it would be better to build our models in spreadsheets to improve the prospects for communication?

This appendix demonstrates that it is, indeed, possible to build a system dynamics models within in a spreadsheet. The demonstration assumes that you have acquired an introductory knowledge of spreadsheets, so you know about rows, columns, cells, etc. But most spreadsheets focus one point in time, so you may have thought of spreadsheets for calculating changes over time. The demonstration builds from the sales force model used in the previous appendices. The appendix concludes with examples where a spreadsheet model would be more useful than a stock-and-flow model.