I've noted before
the importance of thinking appropriately about stocks
. Janice Molloy of Pegasus Communications
just wrote "A Weighty Take on Stocks and Flows" for the August 2008 issue of The Systems Thinker
, using stocks and flows to communicate the message of a New York Times column
by Gail Collins
. It's a good tale; if you subscribe to The Systems Thinker, check it out, or check out the original column.
It was fun talking through the implications of these ideas with Janice, creating a few simple models together to clarify Collins' message, and producing the diagrams that Janice used. There is a message hidden in the fun, though: be sure you understand what they really
mean when someone says they'll reduce the rate at which something is growing. It may not be all that good a deal.
Labels: making sense, system dynamics, systems thinking