Chaos theory and complexity theory, collectively known as nonlinear dynamics or dynamical systems theory, provide a mathematical framework for thinking about change over time. Chaos theory seeks an understanding of simple systems that may change in a sudden, unexpected, or irregular way. Complexity theory focuses on complex systems involving numerous interacting parts, which often give rise to unexpected order. The framework that encompasses both theories is one of nonlinear interactions between variables that give rise to outcomes that are not easily predictable. This entry provides a nonmathematical introduction, discussion of current research, and references for further reading.
Paula T. Morelli and Jon Kei Matsuoka
Social impact assessment (SIA) is the process of analyzing (predicting, evaluating and reflecting) and managing the intended and unintended consequences on the human environment of planned interventions (policies, programs, plans, and projects) and any social change processes brought into play by those interventions so as to bring about a more sustainable and equitable biophysical and human environment (Vanclay, 2002). This subfield of impact assessment attempts to identify future consequences of a current or proposed action related to individuals, organizations and social macro-systems. SIA is policy-oriented social research often referred to as ex-ante evaluation, which involves pre-testing actions/interventions, or analyzing consequences.