Why Systems Engineering?

Why systems engineering? How can that help? Isn’t it enough to let the engineering disciplines do their work and then put the project together?

Systems engineering takes a systems view of the design. It provides more than a simple connection of disparate parts. Systems engineering looks at three systems – the system of interest, the context system, and the system used to design the system of interest. This approach considers the interaction of the components within the design beginning at a high level, conceptual stage in the design and continuing throughout the process. Understanding the design in this way enables the systems engineer to foresee the impacts, positive and negative, that the emerging design will have in the context system.


By predicting the system behavior and interactions with confidence the design team is able to steer the design toward satisfying the requirements efficiently and effectively. In addition, systems engineering links the design domains – requirements, behavior, physical architecture and verification and validation – at every stage in the design. That provides bi-directional traceability from requirements through behavior to architecture and back again, assuring the stakeholders that the system meets its intended purposes.

It is only by taking the systems view and approach in the design process that fit-for-purpose systems devoid of costly unintended consequences can be reliably produced again and again. This has been clearly shown in a recent study (http://www.sei.cmu.edu/library/abstracts/reports/12sr009.cfm). In a joint NDIA, IEEE and SEI sponsored effort, Joe Elm and others surveyed a number of DoD programs looking for evidence of systems engineering practices. They grouped the programs into three levels of system engineering effort: low, middle, and high. They classified the programs’ performance against budget, schedule, and quality as higher, middle, or lower. For the programs using low levels of systems engineering practices the study found only 15% of them achieving a high level of performance. The programs that used high levels of systems engineering practices, however, achieved this success measure 57% of the time.

When the study divided the programs by “program challenge” (basically complexity), the divide widened. In highly complex programs only 8% of the low level systems engineering efforts achieved higher levels of success, while 62% of their systems engineering-oriented counterparts did.

The study succinctly summed up the answer to our question “Why systems engineering?” by stating that “projects that properly apply systems engineering best practices perform better than projects that do not.” It doesn’t get much clearer than that. Systems engineering provides a reliable, repeatable path to project success.


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