Comparison of Commercial System Dynamics Software essay

In the 21st century there is an ever increasing interest in finding solutions to the various environmental, social and economic problems that plague the planet. One of the obvious answers is to formulate and implement effective policies. But a certain policy decision cannot be simply created out of the blue; this must be backed up by long-term studies, extensive research, experiments, etc. Aside from that there is also a need for an interdisciplinary approach especially when it comes to understanding complex ecological systems.

This simply means that a group can easily be bogged down by information overload. Thus, for the past few decades computer software engineers, mathematicians, and other scientists are pooling their talents together in order to build dynamic systems-based software that will be able to accomplish what is humanly impossible. The following pages will describe some of the best systems thinking software available in the market. STELLA One of the most popular systems modeling software available today is the STELLA.

It uses an iconographic interface to facilitate construction of dynamic systems structures (Costanza & Gottlieb, 1998). This means that when constructing models, users have access to cartoon-like icons making work seems like child’s play (Rizzo et al. , 2006). STELLA is a modeler that uses three basic descriptors: stock, which represents quantities or amounts of an entity; a flow, which represents change (flow into or flow out of) a stock; and connector which indicates a relationship (connection) between a stock and a flow (Taffe, 1991).

The great thing about STELLA is that these three descriptors are represented by icons so it is easy for “mathematically less sophisticated” students to use the software (Taffe, 1991). While STELLA is easy to use it is not so impressive when it comes to computational power. For very demanding clients they find STELLA to be somewhat limited, “…when interacting with external data sets and equations…” (Rizzo et al. , 2006). One way of solving this problem according to Ruth, Hannon, and Forrester is to use STELLA in conjunction with other dynamic systems software with higher computational capabilities.

STELLA runs on both Windows and Macintosh platforms. SIMULINK Simulink is a block diagram visual modeling tool that is integrated with MATLAB. But unlike the older versions of MATLAB that can only be used by writing lines of code, Simulink uses an icon based user interface that enables a conceptual diagram of the modeled system (Rizzo et al. 2006). Simulink is a language-based program making it more powerful but increases the learning curve for first time users. It is also difficult to use it without prior knowledge about computer programming languages.

Simulik runs on both Windows and Macintosh platforms. BERKELEY MADONNA This system modeling software was developed in the Berkeley campus hence the name, Berkeley Madonna. It is one of the fastest, general purpose differential equation solver available in the market today. Although it is hard to beat the user-friendly features of STELLA, Madonna can be used to complement the aforementioned easy-to-use software because it can compile the equations from a STELLA model much faster.

And although STELLA is the best choice when it comes to model construction, “…for the determination of the appropriate structure of the model, MADONNA is recommended for sensitivity testing and statistical analyses” (Ruth, Hannon, & Forrester, 1997). One more thing, Madonna can display the results of model runs in graphs and tables; it can also perform statistical fits of model runs to real data by varying parameters and initial conditions (Ruth, Hannon, & Forrester, 1997).

MADONNA runs on both Windows and Macintosh platforms. GOLDSIM GoldSim is powerful software modeling package, a flexible probabilistic simulation platform that can be used to visualise and dynamically simulate nearly all kinds of physical, financial or organisational system (Rizzo et al, 2006). This modeler uses an influence diagram that in turn uses built-in elements that are represented by graphical icons or programming equations (Rizzo et al. , 2006).

Some examples of GoldSim applications include long-term strategic planning, constructing models for disease transmission, evaluating risks for space missions, and assessing the reliability of complicated engineering systems. GoldSim is much more technically advanced than STELLA and Madonna, it has more computational power but it scores low in user-friendliness. To compound problems with usability GoldSim is a language-based program, meaning user needs to be knowledgeable about computer programming languages making it more difficult to use.

GoldSim runs on both Windows and Macintosh platforms. VENSIM Vensim or the Ventana Simulation Environment is a dynamic system software that allows users to conceptualise, build, simulate, analyse, optimise, and deploy models of complex dynamic systems. It is similar to STELLA – it uses stock and flow diagrams and also employs an iconographic interface. Vensim make use of causal loop diagrams. User only has to enter concepts and connect them with arrows. But there are other kinds of diagrams that can be used in Vensim including flow charts, organizational charts, and even fishbone diagrams.

The user interface is enhanced with an intuitive “Workbench-Toolbox” that allows for easy identification of variables as well as the display of simulation results (Vensim Product Center, 2007). Vensim runs on both Windows and Macintosh platform. POWERSIM The name comes from “Powerful Simulation. ” This software is similar to STELLA. It also uses iconographic interface. This dynamic system software also employs “flow diagram symbols” making it easier for less sophisticated users to immediately build models or as the name suggest creates business and economic simulations.

According to Chapman, Powersim is much better than STELLA because it has more in-built functions and he adds, “A powerful heuristic features of these packages is that they allow for the on-screen construction of flow-chart style representation of a model, in much the same way one would develop a conceptual flow chart on paper … one only has to add the governing equations in order to begin a simulation” (1997). The only thing going against this software is its price; it is more expensive than the rest of the products mentioned earlier. PowerSim runs on both Windows and Macintosh platforms.