System Dynamics Society
System dynamics is a methodology for studying and managing
        complex feedback systems, such as one finds in business and other social
        systems. In fact it has been used to address practically every sort of
        feedback system. While the word system has been applied to all sorts of
        situations, feedback is the differentiating descriptor here. Feedback
        refers to the situation of X affecting Y and Y in turn affecting X perhaps
        through a chain of causes and effects. One cannot study the link between
        X and Y and, independently, the link between Y and X and predict how the
        system will behave. Only the study of the whole system as a feedback system
        will lead to correct results.