System dynamics software (such as Stella, iThink, Vensim, and Powersim) is based on the standard stock and flow approach developed by Professor Jay W. Forrester at MIT in the late 1950s and early 1960s. Models based on system dynamics are built using three principal element types (stocks, flows, and converters), and put emphasis on understanding the feedback structure of systems. System dynamics software packages are typically used for simulating business and organizational systems and simple engineering and scientific systems.
Although GoldSim is similar to system dynamics programs in many ways (and can simulate any kind of system that these tools can), GoldSim moves beyond the relatively restrictive stock and flow syntax in order to more realistically model complex systems. In particular, GoldSim differs from most system dynamics software packages by offering the following features:
- GoldSim includes a much broader range of model objects (elements) that make the model logic and structure more transparent.
- GoldSim provides powerful capabilities for superimposing the occurrence and consequences of discrete events (e.g., financial transactions, accidents, labor strikes, lawsuits) onto continuous systems.
- GoldSim was specifically designed to quantitatively represent uncertain parameters and stochastic processes and events in the system. Because nearly all real-world systems are strongly influenced by such parameters, processes and events, predictive simulations must include a realistic representation of such system features.
- GoldSim's hierarchical submodel approach and other specialized programming features (e.g., local variables, looping/iterative submodels) allow you to build and efficiently maintain highly complex models (consisting of thousands of objects) without losing the ability to explain the models to a non-technical audience.
- GoldSim is dimensionally aware and allows you to use any kind of units in your model. GoldSim checks for dimensional consistency and carries out the conversions for you automatically during model construction.
- GoldSim was designed to accommodate the addition of specialized extension modules to realistically address systems that can not adequately be represented using the stock and flow paradigm. This includes the Financial Module (for simulating financial instruments and associated stochastic processes), the Contaminant Transport Module (for simulating the coupled fate and transport of chemical and radioactive constituents in the environment) and the Reliability Module (for simulating the reliability of complex engineered systems).