Editing System dynamics (section)

===Causal loop diagrams===
{{Main article|Causal loop diagram}}
In the system dynamics methodology, a problem or a system (e.g., ecosystem, political system or mechanical system) may be represented as a [[causal loop diagram]].<ref>{{cite book |last=Sterman |first=John D. |year=2000 |title=Business Dynamics: Systems Thinking and Modeling for a Complex World |location=Boston |publisher=McGraw-Hill |isbn=0-07-231135-5 }}</ref> A causal loop diagram is a simple map of a system with all its constituent components and their interactions. By capturing interactions and consequently the feedback loops (see figure below), a causal loop diagram reveals the structure of a system. By understanding the structure of a system, it becomes possible to ascertain a system's behavior over a certain time period.<ref>Meadows, Donella. (2008). Thinking in Systems: A Primer. Earthscan</ref>

The causal loop diagram of the new product introduction may look as follows:

[[Image:Adoption CLD.svg|centre|Causal loop diagram of ''New product adoption'' model|frame]]

There are two feedback loops in this diagram.  The positive reinforcement (labeled R) loop on the right indicates that the more people have already adopted the new product, the stronger the word-of-mouth impact.  There will be more references to the product, more demonstrations, and more reviews.  This positive feedback should generate sales that continue to grow.

The second feedback loop on the left is negative reinforcement (or "balancing" and hence labeled B).  Clearly, growth cannot continue forever, because as more and more people adopt, there remain fewer and fewer potential adopters.

Both feedback loops act simultaneously, but at different times they may have different strengths.  Thus one might expect growing sales in the initial years, and then declining sales in the later years. However, in general a causal loop diagram does not specify the structure of a system sufficiently to permit determination of its behavior from the visual representation alone.<ref>{{cite journal |last=Richardson |first=G. P. |year=1986 |title=Problems with causal-loop diagrams |journal=Syst. Dyn. Rev. |volume=2 |issue= 2|pages=158–170 |doi=10.1002/sdr.4260020207 }}</ref>