The Oxford English Dictionary defines a system as, “A set of things working together as parts of a mechanism or an interconnecting network; a complex whole.” There are, of course, a range of specific kinds of systems, including economic systems, computer systems, biological systems, social systems, psychological systems, etc. In each of these domains, the system includes specialization of component parts (a division of labor), boundaries for each of the constituent parts, both a degree of relative autonomy and an interdependence of each part on the functioning of the other parts of that system, long-term functioning (i.e. function over time), and the production of outcomes (whether such outcomes are intended or not). Systems produce effects.
While various systems are distinct, there has been an effort to generate a general science of systems, under the umbrella of “systems theory” (See, for example, this summary, “Systems Theory” ) Theorists have attempted to construct a general and abstract science that is able to describe a variety of systems. These efforts, although subject to some questions and criticisms, have been useful for mapping and describing a variety of systems and structures, and have helped social scientists and organizational/social change advocates to describe approaches to intervening in a variety of contexts, including organizational, educational, social welfare, and economic systems.
Systems thinking—or thinking about systems vs. thinking exclusively about individuals or single events, can help those who are attempting to strengthen initiatives and interventions. As Michael Goodman points out in “Systems Thinking: What, Why, When, Where, and How?” “Systems thinking often involves moving from observing events or data, to identifying patterns of behavior over time, (and) to surfacing the underlying structures that drive those events and patterns. By understanding and changing structures that are not serving us well (including our mental models and perceptions), we can expand the choices available to us and create more satisfying, long-term solutions to chronic problems.”
Program evaluation benefits from a systems approach because interventions (e.g., programs and initiatives) are themselves systems, and are embedded or nested in larger social and economic systems. Rather than thinking that challenges to program effectiveness are the exclusive result of individuals’ one-off actions, it is more productive to examine the systemic features of the program in order to identify how both internal structures and repeated behaviors, and larger external systemic constraints shape programs’ effectiveness.