Without the computer to handle the myriad causal relationships and niggling mathematical details, the relationship between microstructure and macrodynamics would remain hidden. Nevertheless, computation's contribution is not purely empirical and data related. Performing such analyses requires a different set of motivations, assumptions, and conceptions as well as a new language that effectively allows for their expression. Within system dynamics, components are expressed as stocks, which are simply quantities, like water in a bathtub. Flows are then attached so that the stock may be filled or drained.
Flows allow the level of a stock to vary over time, making the model dynamic.
Nonlinearity makes the mathematics more complicated, but it pays dividends by allowing systems to be represented more accurately. That is, as A influences B , B can in turn influence A , forming a feedback loop . Multiple, interconnected feedback loops can be represented in a system dynamics model. Feedback, like nonlinearity, makes the system both more complex and realistic. Feedback Loop Issues of system representation have consequences beyond the mathematical.