All you wanted to do was put a bird feeder in your yard to attract birds and make for a more pleasant morning. And...

This Romeo and Juliet Model was adapted by Geoff McDonnell from Michael J Radzicki (1993) Dyadic processes, tempestuous relationships, and system dynamics, System Dynamic Rev. 9 (1) :79-94

The structure responsible for rabbit population growth.

While these pictures represent very different things there is a common essence.

Consider the following "Sustaining the Forest" model intended to provide another example of how unexpected the behavior of a web of extended interactions can be.

Simplest Innovation diffusion model from Sterman's Business Dynamics Ch 9

There are limits to what one can infer from a qualitative model.

All you wanted to do was put a bird feeder in your yard to attract birds and make for a more pleasant morning. And...

The interaction of a population of Moose and Wolves.

All you wanted to do was put a bird feeder in your yard to attract birds and make for a more pleasant morning. And...

Simplest Innovation diffusion model from Sterman's Business Dynamics Ch 9

While these pictures represent very different things there is a common essence.

Little Red Riding Hood walking through the woods to Grandma's house. How long will it take?

Consider the following "Sustaining the Forest" model intended to provide another example of how unexpected the behavior of a web of extended interactions can be.

The interaction of a population of Moose and Wolves.

The interaction of a population of Moose and Wolves.

This model is derived from the paper "Nobody Ever Gets Credit for Fixing Problems that Never Happened: Creating and Sustaining Process Improvement" by Nelson P. Repenning and John D Sterman. See Insight 752 for a causal loop version of this model.

Little Red Riding Hood walking through the woods to Grandma's house. How long will it take?

The interaction of a population of Moose and Wolves.

Yesterday's actions are responsible for the world we experience today. And today's actions are responsible for the world that we will experience tomorrow. The "Creating the Future" model is intended to provide a better sense of the common process associated with the unexpected unfolding of the future..

The interaction of a population of Moose and Wolves.

There are about fifteen known archetypes with an interesting set of relationships among them.

There is a new version of this model at

Frequently Recurring Structures

There's actually more to filling a swimming pool with water than you might realize.