Figure 3.

Characterizations of two types of simulation. Illustrated are work activities built upon explanations carried forward from I and II. Simulation operation is not illustrated. A requirement for both types of simulation is that output (specific computed solutions) match target phenomenon measurements within some tolerance. (a) Starting with a Mechanistic Explanation (I), the modeler completes two tasks. (1) Develop relational and continuum mathematical descriptions of the mechanistic explanation’s salient information. (2) Faithfully instantiate in software all mathematical descriptions such that computed solutions simulate the output envisioned by those mathematical descriptions. The resulting system provides a Simulation of a Mechanistic Explanation. Before publication, the system has typically undergone several rounds of refinement and revision. (b) Starting with II, the modeler develops the mathematical descriptions needed to provide faithful characterizations of the analogous mechanism’s salient features during operation. The requirements for software instantiation are the same as for a. The resulting system simulates output from II as if it were real. Red asterisks: characteristics that distinguish b from a.