Overview of the Systems Approach
This article considers the question, "what is the systems approach and how does it relate to systems engineering (SE)?". This question is discussed in general terms here and expanded upon in the other articles, which detail parts of the approach. The final article in this knowledge area, Applying the Systems Approach, then returns to this question and considers the dynamic aspects of how the approach is used and how this relates in detail to elements of systems engineering.
Definition and Uses of Systems Approach
According to Ryan (2008), the systems approach and SE formed and grew somewhat independently, but are highly related and compatible. Both are based on the concepts of systems thinking that produce a broader understanding of the challenges being faced, the environment, and all of the related parts of the solution. Good SE process and lifecycle descriptions are based upon the systems approach. The best systems engineers must be good systems thinkers and should understand and apply a systems approach to all challenges and problems that they face when conducting SE.
The systems approach is essential when reductionist assumptions (i.e., the whole system has properties derived directly from the properties of their components) no longer apply to the system of interest (SoI). Emergent properties at the system level, which cannot be derived from a summation of the subsystem properties, necessitate a holistic systems approach. The systems approach is often invoked in applications beyond product systems. For example, the systems approach can be used in the educational domain. According to Biggs (1993), the system of interest includes “the student, the classroom, the institution, and the community.” In fact, as the founder of systems thinking and systems science, Ludvig von Bertalanffy (1968), points out, “Systems are everywhere.”
The goal of the systems approach is to understand the organization of ideas and to view problems and solutions holistically. It views the organization of ideas as a compound concept that incorporates structure and behavior of related systems associated with a problem and its possible solutions. It has resulted in a loosely connected set of techniques, where each technique contributes some insight on systemic aspects of problem or solution systems and helps us deal with different aspects of complexity . Because no single technique provides a complete understanding, knowledge of the limits of applicability of individual techniques is central to any systems approach. Most “situation systems” and “respondent systems” (see Figure 1) that systems engineers deal with require a combination of both hard and soft methods. An integration of hard and soft methods is an important aspect of the systems approach.
Lawson (2010) describes the relationship among the systems approach, systems thinking, and SE as a mindset to “think” and “act” in terms of systems. Developing this mindset is promoted by several paradigms including the system coupling diagram , which includes the elements "situation system", "respondent system", and "system assets" (see Figure 1).
- The situation system is the problem or opportunity situation, either unplanned or planned. The situation may be the work of nature, man-made, a combination of both natural and man-made, or a postulated situation that is to be used as a basis for deeper understanding and training (e.g., business games or military exercises).
- The respondent system is the system created to respond to the situation. The parallel bars indicate that this system interacts with the situation and transforms the situation into a new situation. Based on the situation that is being treated, a respondent system can have several names, such as project, program, mission, task force, or in a scientific context, experiment. One of the system elements of this system is a control element that directs the operation of the respondent system in its interaction with the situation. This element is based on an instantiation of a control system asset; e.g., a command and control system or a control process of some form.
- System assets are the sustained assets of one or more enterprises to be used in response to situations. System assets must be adequately managed throughout the life cycle so they will perform their function when instantiated in a respondent system. These assets are the primary objects for systems engineers. Examples of assets include value-added products or services, facilities, instruments and tools, and abstract systems, such as theories, knowledge, processes, and methods.
Lawson's model portrays one aspect of the systems approach and is applicable to understanding a problem; it organizes the resolution of that problem and creates and integrates any relevant solutions to enable that solution. Since the systems approach is a mindset prerequisite to SE, the premise is that projects and programs executed with this mindset are more likely to solve an idenfitied problem or take advantage of an identified opportunity.
The systems approach described in the SEBoK uses the following general problem understanding and resolution activities:
- identify and understand the relationships between the potential problems and opportunities in a real world situation;
- fully understand and describe a selected problem or opportunity in the context of its wider system and its environment;
- synthesize viable system solutions to a selected problem or opportunity situation;
- analyze and choose between alternative solutions for a given time/cost/quality version of the problem;
- provide evidence that a solution has been correctly implemented and integrated; and
- deploy, sustain, and use a solution to help solve the problem (or exploit the opportunity).
All of the above are considered within a life cycle framework which may need concurrent, recursive and iterative applications of some or all of the systems approach. Activities 1 and 6 are part of the business cycles of providing stakeholder value (Ring 2004) within an enterprise, whereas activities 2-5 can be mapped directly to product, service, and enterprise engineering life cycles. A distinction is made here between the normal business of an enterprise and the longer-term strategic activities of Enterprise Systems Engineering.
When the systems approach is executed in the real world of an engineered system , a number of engineering and management disciplines emerge, including SE. SEBoK Parts 3 and 4 contain a detailed guide to SE with references to the principles of the systems approach as relevant.
SEBoK Part 5 provides a guide to the relationships between SE and the organizations, and Part 6 provides a guide to the relationship between SE and other disciplines. More detailed discussion of how the systems approach relates to these engineering and management disciplines is included in the Applying the Systems Approach topic in this knowledge area.
References
Works Cited
Biggs, J.B. 1993. "From Theory to Practice: A Cognitive Systems Approach". Journal of Higher Education & Development. Available from http://www.informaworld.com/smpp/content~db=all~content=a758503083.
Boardman, J. and B. Sauser 2008. Systems Thinking - Coping with 21st Century Problems. Boca Raton, FL, USA: CRC Press.
Checkland, P. 1999. Systems Thinking, Systems Practice. New York, NY, USA: John Wiley & Sons.
Edson, R. 2008. Systems Thinking. Applied. A Primer. Arlington, VA, USA: Applied Systems Thinking (ASysT) Institute, Analytic Services Inc.
Lawson, H. 2010. A Journey Through the Systems Landscape. London, UK: College Publications, Kings College.
Senge, P.M. 1990. The Fifth Discipline: The Art and Practice of the Learning Organization. New York, NY, USA: Doubleday/Currency.
Ryan, A. 2008. “What is a Systems Approach?” Journal of Non-linear Science.
Ring J. 2004. "Seeing an Enterprise as a System". INCOSE Insight. 6(2) (January 2004): 7-8.
vonBertalanffy, L. 1968. General Systems Theory. New York, Ny, USA: George Braziller, Inc.
Primary References
Boardman, J. and B. Sauser 2008. Systems Thinking: Coping with 21st Century Problems. Boca Raton, FL, USA: CRC Press.
Checkland, P. 1999. Systems Thinking, Systems Practice. New York, NY, USA: John Wiley & Sons.
Senge, Peter. M. 1990. The Fifth Discipline: The Art and Practice of the Learning Organization. New York: Doubleday/Currency.
Additional References
Biggs, J.B. 1993. "From Theory to Practice: A Cognitive Systems Approach". Journal of Higher Education & Development.. Available from http://www.informaworld.com/smpp/content~db=all~content=a758503083.
Edson, R. 2008. Systems Thinking. Applied. A Primer. Arlington, VA, USA: Applied Systems Thinking (ASysT) Institute, Analytic Services Inc.
Lawson, H. 2010. A Journey Through the Systems Landscape. London, UK: College Publications, Kings College.
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