Restructuring Change, Interpreting Changes: The DeltaTick Modeling and Analysis Toolkit

Understanding how and why systems change over time is a powerful way to make sense of and navigate our world. By modeling those systems, learners have the opportunity to consider how their own actions influence the world, and to make predictions and recommendations for the future. But often, the very notion of change is as complex as it is powerful - population levels, global temperatures, or economic trends are all driven by multiple events and actors, but measured in terms of only a few quantities. In this paper, we discuss the motivation, design, and pilot user studies of DeltaTick, an extension to the NetLogo (Wilensky, 1999) agent-based modeling environment that allows students to easily build and analyze sophisticated models of quantitative change within specific real-world domains. To do so, they construct models in terms of agent behavior-based units, rather than the rate-based units typical of calculus-based or system dynamics models. They can then explore those models with specific attention to plots of quantitative trends that result, providing multiple opportunities for them to connect and compare their behavioral models to typical equation-based representations.