(As in any teaching environment I'd try to be very aware of non-verbal responses from my listener.)
'As one example we could consider the salmon ecosystem which includes fish, predators, commercial and sports fishermen, the physical environment (cold, clear, running water with gravel beds vs. clearcutting, grazing, silt, and warm water), dams, turbines, and fishladders.' (I'd try to create as broad a laundry list as possible, perhaps drawing my listener in to provide suggestions as well.)
'Another very different example might be the criminal justice system, which includes jails, policemen, judges, criminals, probation offiicers, victims, families, and the perceptions of the general public.'
'I need to give you several examples here, because system dynamics is not a 'sociology' tool, or an 'ecology' tool, or a 'financial' tool. It is a more general tool that let's us think about, and study, systems in general."
'System Dynamics provides us with two major tools. First is a very simple, but powerful way to develop DIAGRAMS which specifically help us talk to each other about the parts of a system and how they fit together. As we build a diagram together we are forced to talk about our underlying ideas and assumptions, so they become much less fuzzy. We may find that we -cannot- build a diagram that we both agree with. This is a HUGE step forward, because now we have at least clarified our own understanding, and increased our understanding of the other person's 'mental model'.'
'After we have developed a diagram, System Dynamics software allows us to put numbers on each piece of the puzzle, or on each connection between two or more pieces of the puzzle. Then we can run computer simulations which describe the behavior of the 'system' under different conditions (more dams, fewer dams; more rain, less rain; more logging, less logging).
Is the model 'right'? We don't know for sure. It can never be 'perfect'.
Does it help us understand the system? Yes! Does it increase our awareness of other factors that may be outside our usual viewpoint? Yes! Does it allow us to talk more intelligently to our colleagues, our kids, and our politicians? Yes! This approach will very often identify 'fixes that fail', despite the best intentions of idealistic policy makers. And hopefully, it will lead us to fixes that don't fail . . . "
Excerpt from an email to the system dynamics listserv by
Ed Gallaher
Assoc. Prof. Pharmacology and Behavioral Neuroscience
Oregon Health Sciences University
Portland, OR