in Large Complex Projects
FEATURED PAPER
By Bob Prieto
Florida, USA
Abstract
Assumptions underpin planning and execution in engineering and construction projects yet migrate over time, compounding uncertainty and driving cost, schedule, and performance deviation. This paper develops a rigorous Assumption Governance Index (AGI)[1] and category-level indices that quantify assumption migration, incorporate consequence weighting and confidence decay[2], and support statistical monitoring of mean and dispersion dynamics. The methodology embeds principles from Quantum Project Management[3] (QPM) to address entanglement, emergence, and measurement feedback common to large complex projects. Validation approaches, implementation architecture, and governance decision rules are described. The AGI supports timely rebaselining, targeted mitigations, and adaptive governance for projects where traditional decomposition and deterministic controls are insufficient[4].
The paper also develops a companion Assumption Diffusion Index (ADI)[5] that measures how widely and how quickly changes to an assumption’s state (migration, rebaseline, or reprioritization) propagate across the assumption register[6] and through entangled clusters. Where AGI summarizes the magnitude and weighted impact of assumptions at a point in time, ADI captures the spread, velocity, and reach of those changes through the system.
Introduction
Large complex projects (LCPs) in engineering and construction depend on a network of explicit and tacit assumptions spanning technical, environmental, stakeholder, economic, client, and productivity dimensions. These assumptions represent the team’s best assessment at a given moment but are inherently uncertain and subject to migration as external and internal conditions evolve. Systematic tracking of assumptions in general, and assumption migration in particular, is essential for governance, rebaselining, contingency allocation, and strategic decision-making. This paper introduces a singular Assumption Governance Index (AGI) plus category-specific indices and statistical measures to monitor migration dynamics and support governance actions in the context of QPM’s entanglement-aware view of LCPs[7].
Similarly, it introduces an Assumption Diffusion Index (ADI) that provides significant and important insights into:
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- Propagation dynamics — shows whether an assumption change is isolated or rapidly influences many others (contagion vs local event).
- Velocity — quantifies how fast migrations travel through clusters
- Network reach — identifies central assumptions that act as diffusion hubs even if their instantaneous migration is small.
- Fragility vs concentration — discriminates between portfolios that have similar AGI levels but very different systemic fragility (one dominated by a few high impact change items versus one where small changes cascade).
- Early-warning for systemic escalation — high ADI for a small migration signals risk of future AGI jumps; AGI itself can lag because it is a snapshot of current weighted contributions.
Assumption Migration
Assumption migration is a persistent driver of program instability: small, untracked changes in many assumptions can compound into large, unexpected impacts on cost, schedule, quality, and strategic value.
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How to cite this paper: Prieto, R. (2025). Metrics for Assumption Management in Large Complex Projects, PM World Journal, Vol. XIV, Issue XII, December. Available online at https://pmworldlibrary.net/wp-content/uploads/2025/12/pmwj159-Dec2025-Prieto-metrics-for-assumption-management-large-complex-projects.pdf
About the Author
Bob Prieto
Chairman & CEO
Strategic Program Management LLC
Jupiter, Florida, USA
Bob Prieto is Chairman & CEO of Strategic Program Management LLC focused on strengthening engineering and construction organizations and improving capital efficiency in large capital construction programs. Previously, Bob was a senior vice president of Fluor, focused on the development, delivery, and turnaround of large, complex projects worldwide across all of the firm’s business lines; and Chairman of Parsons Brinckerhoff, where he led growth initiatives throughout his career with the firm.
Bob’s board level experience includes Parsons Brinckerhoff (Chairman); Cardno (ASX listed; non-executive director); Mott MacDonald (Independent Member of the Shareholders Committee); and Dar al Riyadh Group (current)
Bob consults with owners of large, complex capital asset programs in the development of programmatic delivery strategies encompassing planning, engineering, procurement, construction, financing, and enterprise asset management. He has assisted engineering and construction organizations to improve their strategy and execution and has served as an executive coach to a new CEO. He is author of eleven books, over 1000 papers and National Academy of Construction Executive Insights, and an inventor on 4 issued patents.
Bob’s industry involvement includes the National Academy of Construction and Fellow of the Construction Management Association of America (CMAA). He serves on the New York University Tandon School of Engineering Department of Civil and Urban Engineering Advisory Board and New York University Abu Dhabi Engineering Academic Advisory Council and previously served as a trustee of Polytechnic University. He has served on the Millennium Challenge Corporation Advisory Board and ASCE Industry Leaders Council. He received the ASCE Outstanding Projects and Leaders (OPAL) award in Management (2024). He was appointed as an honorary global advisor for the PM World Journal and Library.
Bob served until 2006 as one of three U.S. presidential appointees to the Asia Pacific Economic Cooperation (APEC) Business Advisory Council (ABAC). He chaired the World Economic Forum’s Engineering & Construction Governors and co-chaired the infrastructure task force in New York after 9/11. He can be contacted at rpstrategic@comcast.net.
To see more works by Bob Prieto, visit his author showcase in the PM World Library at https://pmworldlibrary.net/authors/bob-prieto/
[1] The AGI is a normalized, consequence‑weighted index summarizing per‑assumption migration, time‑aware confidence, and amplification adjustments to produce a governance‑grade KPI; it is intended as a lead indicator for rebaseline and contingency decisions. See Section 1.4 and Appendix B for the formal formula and worked example.
[2] Confidence decay, Ci(t) is the time‑ and event‑modulated confidence for assumption i (default exponential decay) used to increase sensitivity to older, less‑tested assumptions. It changes how much a given migration contributes to AGI; see Section 1.3.3 for the decay formula and event amplification notes.
[3] Prieto, R. “Quantum Project Management: A monograph on a new theory for management of large complex projects”; ISBN: 978-1-304-08165-0, December 2024
[4] Prieto, R. “Quantum Project Management.” PM World Journal feature paper, January 2024
[5] The ADI quantifies how an assumption change propagates through the entanglement network by reporting footprint, velocity, and reach over a chosen horizon; ADI complements AGI by showing propagation potential rather than instantaneous magnitude. See Section 2.0 and Appendix D (dashboard footprints) for computation and use cases
[6] Even the existence of a comprehensive written Assumption Register is a rarity in too many LCPs
[7] Prieto, B. “Management of Assumption Infatuation in Large Complex Projects.” PM World Journal archive, April 2016. https://pmworldlibrary.net/wp-content/uploads/2016/04/pmwj45-Apr2016-Prieto-Management-of-Assumption-Infatuation-in-Large-Complex-Projects.pdf
