Analysis and Selection between Alternative Solutions

According to the Oxford English Dictionary (OED 1973), analysis is “the resolution of anything complex into its simple elements.” This article briefly discusses the nature of systems analysis using a systems approach. Any of the activities described below may need to be considered concurrently through the systems' life, as discussed in the Applying the Systems Approach article. Systems analysis assumes that the problem or opportunity that the system is intended to address has previously been identified and understood or, more likely for any non-trivial system, is being identified and understood concurrently with system analysis activities.

The elements of system analysis discussed below are: Identification of the Elements of a System, Division of Elements into Smaller Elements, Grouping of Elements, Identification of the Boundary of a System, Identification of the Function of Each Element, and Identification of the Interactions Among the Elements.

Identification of the Elements of a System

The systems approach calls for the identification of the elements of a system, and this concept of elements is critical. (Jackson et al. 2010, pp. 41-42) identify the kinds of elements that make up a system. Typical elements treated within Systems Engineering (SE) may be hardware, software, humans, processes, conceptual ideas, or any combination of these. SE defines the properties of these elements, verifies their capability, and validates the capability of the entire system. According to (Page 2009), in complex systems the individual elements of the system are characterized by their adaptability.

In a SE context, according to (Blanchard and Fabrycky 2006, p. 7) elements may be physical, conceptual, or processes. Physical elements may be hardware, software, or humans. Conceptual elements may be ideas, plans, concepts, or hypotheses. Processes may be mental, mental-motor (writing, drawing, etc.), mechanical, or electronic.

In addition to the operational elements of the system under consideration (i.e., a System of Interest, SOI), ISO/IEC 15288 (2008) also calls for the identification of the enabling systems. These are systems utilized at various stages in the life cycle; for example, maintenance and other systems that support the operational elements to solve problems or achieve opportunity.

Today's systems often include existing elements. It is rare to find a true "greenfield" systems in which the developers can specify and implement all new elements from scratch. "Brownfield" systems are much more typical, where legacy elements constrain the system architecture, capabilities, technology choices, and other aspects of implementation. (Boehm 2009)

Division of Elements into Smaller Elements

The next aspect of the Systems Approach is that elements can be divided into smaller elements. The division of elements into smaller elements allows the systems to be grouped, and leads to the Systems Engineering concept of physical architecture as described by (Levin 2009, pp. 493-495). Each layer of division leads to another layer of the hierarchical view of a system. As Levin points out, there are many ways to depict the physical architecture including wiring diagrams, block diagrams, etc. All of these views depend on arranging the elements and dividing them into smaller elements. According to the principle of recursion, these decomposed elements are either terminal elements or are further decomposable.

Grouping of Elements

The next aspect of the systems approach is that elements can be grouped. This leads to the identification of the subsystems essential to the definition of a system. SE determines how a system may be partitioned and how each subsystem fits and functions within the whole system. The grouping of all the elements of a system is called the system of interest (SOI), also called the relevant system by (Checkland 1999, p. 166). The SOI is the focus of the SE effort. According to (Hitchins 2009, p. 61), some of the properties of an SOI are as follows: the SOI is open and dynamic; the SOI interacts with other systems, and; the SOI contains sub-systems. The SOI is brought together through the concept of synthesis.

Identification of the Boundary of a System

Establishing the boundary of a system is essential to SE and the determination of the system's interaction with its environment and with other systems and the extent of the system of interest (SOI). (Buede 2009, p. 1102) provides a comprehensive discussion of the importance and methods of defining the boundary of a system in a SE context.

Identification of the Function of Each Element

The function of a system or of its elements is essential to SE and the determination of the purpose of the system or of its elements. (Buede 2009, pp. 1091-1126) provides a comprehensive description of functional analysis in a SE context.

Identification of the Interactions among the Elements

The next element of the systems approach is the identification of the interactions among the elements. These interactions lead to the SE process of interface analysis. Integral to this aspect is the principle of interactions. Interactions occur both with other system elements and also with external elements and the environment. In a SE context, interfaces have both a technical and managerial importance. (Browning 2009, pp. 1418-1419) provides a list of desirable characteristics of both technical and managerial interface characteristics.

Linkages to other topics

Applying the Systems Approach

References

Citations

Blanchard, B. and Fabrcky, W. J. 2006. Systems Engineering and Analysis. Upper Saddle River, NJ: Prentise Hall.

Boehm, B. 2009. "Applying the Incremental Commitment Model to Brownfield System Development". Proceedings of the 7th Annual Conference on Systems Engineering Research". Loughborough, UK.

Browning, T. R. 2009. "Using the Design Structure Matrix to Design Program Organizations". In Sage, A.P. and Rouse, W. B. (eds.) Handbook of Systems Engineering and Management. (2nd ed.). Hoboken, NJ: John Wiley & Sons.

Buede, D. M. 2009. "Functional Analysis". In: Sage, A. P. & Rouse, W. B. (eds.) Handbook of Systems Engineering and Management. (2nd. Hoboken, NJ: John Wiley & Sons.

Checkand, P. 1999. Systems Thinking, Systems Practice, New York, NY, USA: John Wiley & Sons.

Jackson, S., Hitchins, D. & Eisner, H. 2010. "What is the Systems Approach?". INCOSE Insight. International Council on Systems Engineering.

Levin, A. H. 2009. "System Architectures". In Sage, A. P. & Rouse, W. B. (eds.) Handbook of Systems Engineeering and Management. (2nd ed.). Hoboken, NJ: John Wiley & Sons.

Page, S. E. 2009. Understanding Complexity. The Great Courses. Chantilly, VA, USA: The Teaching Company.

OED 1973. In Onions, C. T. (ed.) The Shorter Oxford English Dictionary on Historical Principles. (3rd ed.). Oxford, UK: Oxford Univeristy Press.

Primary References

ISO/IEC 2008. Systems and software engineering -- System life cycle processes. ISO/IEC/IEEE 15288:2008. Geneva, Switzerland: International Organisation for Standardisation / International Electrotechnical Commissions.

Jackson, S., Hitchins, D. and Eisner, H. 2010. "What is the Systems Approach?". INCOSE Insight, 13(1), April 2010, p. 41-42. San Diego, CA, USA: International Council on Systems Engineering.

Additional References

Blanchard, B. & Fabrcky, W. J. 2006. Systems Engineering and Analysis. Upper Saddle River, NJ: Prentise Hall.

Browning, T. R. 2009. "Using the Design Structure Matrix to Design Program Organizations". In Sage, A.P. and Rouse, W.B. (eds.) Handbook of Systems Engineering and Management (2nd Ed.). Hoboken, NJ: John Wiley & Sons.

Buede, D. M. 2009. "Functional Analysis". In Sage, A.P. and Rouse, W.B.. (eds.) Handbook of Systems Engineering and Management. Second ed. Hoboken, NJ: John Wiley & Sons.

Levin, A. H. 2009. System Architectures. In Sage, A.P. and Rouse, W.B. (eds.) Handbook of Systems Engineeering and Management. Second ed. Hoboken, NJ: John Wiley & Sons.

Page, S. E. 2009. Understanding Complexity. The Great Courses. Chantilly, VA, USA: The Teaching Company.