Assaying the importance of system complexity for the systems engineering community

Abstract

How should organizations approach the evaluation of system complexity at the early stages of system design in order to inform decision making? Since system complexity can be understood and approached in several different ways, such evaluation is challenging. In this study, we define the term “system complexity factors” to refer to a range of different aspects of system complexity that may contribute differentially to systems engineering outcomes. Views on the absolute and relative importance of these factors for early–life cycle system evaluation are collected and analyzed using a qualitative questionnaire of International Council on Systems Engineers (INCOSE) members (n = 55). We identified and described the following trends in the data: there is little between‐participant agreement on the relative importance of system complexity factors, even for participants with a shared background and role; participants tend to be internally consistent in their ratings of the relative importance of system complexity factors. Given the lack of alignment on the relative importance of system complexity factors, we argue that successful evaluation of system complexity can be better ensured by explicit determination and discussion of the (possibly implicit) perspective(s) on system complexity that are being taken.

Evaluating the complexity of engineered systems: A framework informed by a user case study

“…A previous study collected judgments from current systems engineering practitioners on the relative and absolute importance of several different system complexity factors identified that additional relevant system complexity factors could include consideration of the number and diversity of system interfaces and dependencies, nonfunctional requirements, and “client/customer/user complexity (e.g., their understanding of the system, novelty of the system to them, willingness to accept change).” 86 For the Thales Group “Complexity Profiler,” this finding implicates that the complexity factors encoded in the tool requires updating, preferably via a combination of literature survey and a survey of experienced systems engineering managers from across the organization. However, care must be taken with the addition of more system complexity factors to such tools to ensure that the factors are adequately and unambiguously defined.…”

“…The lack of a consensus view within the systems engineering community on the relative importance of different system complexity factors causes an additional challenge. That systems engineers are not aligned with each other on how important system complexity factors are, and may not appreciate the extent or nature of these misalignments, may hinder efforts to effectively identify, evaluate, and manage sources of system complexity 86 …”

“…That many respondents found the “Complexity Profiler” to be useful is a positive indicator, and while the tool is flawed, it is encouraging that the organization has started this line of enquiry and can make improvements in the future. It is a positive feature that the organization has invested effort in understanding the impact of complexity on their systems, given that many systems engineers have not been systematically engaged in an evaluation activity like this as part of their practice or training 86 …”

Toward an integrated project complexity narrative – A case study of academic organizations

“…In turn, organizations that recognize these distinctions realize a better understanding of the interplay of scientific and heuristic pathways driving the emergence and evolution of system principles and methods across science and engineering fields 26 . We assert there are benefits, both practical and philosophical, for organizations to embrace an integrated project complexity narrative that addresses the challenges associated with contested definitions of systems complexity 15,68 and project complexity 5,54 …”

“…This aligns with the three types of structural complexity described by Sheard and Mostashari 17 that is, size, architecture and connectivity. It is also the type of complexity that has seen the most extensive development of complexity metrics 16,68,69 and the concept with the most mentions in both project and system complexity literature. Structural complexity should be understood as applicable to both engineered systems and the organizations put in place to deliver them.…”