| The Idagon model is considerably more complicated than
the models in Modeling the Environment. It is comprised of nine sectors.
In building each sector, I followed the advice on page 204 of the book ---
keep the sector "sufficiently simple that we can see every variable
and every connection on a single page." But by the time the sectors
were combined into one model, the complexity was elevated to a level beyond
the examples in the book. You should also know that the model uses cryptic names. If you do look inside the model, you'll be able to guess some of the stocks (i.e., water stored in American Lake or water stored in the aquifer), and you might be able to guess the meaning of some of the flows. But you won't be able to learn much more from studying the flow diagram or the equations. The Idagon was designed quite differently from the three "flight simulators" in the book. All three simulators were designed as "one page" models with relatively clear variable names. You can look inside the Tucannon Harvest Simulator (page 166), the feebate control model (page 262) and daisyworld simulator (page 275) and learn from their stock-and-flow structure. (Indeed, some of the exercises challenge you to build and verify the original models.) The Idagon was not designed to be used in this manner, so don't be disappointed when you can't make sense out of the flow diagram or the equations. |