Management of Assumption Infatuation in Large Complex Projects


By Bob Prieto

Chairman & CEO

Strategic Program Management LLC

Florida, USA

We love assumptions. In fact when it comes to large engineering and construction projects we have come to love them so much that we take them for granted. Subconsciously, or maybe it is unconsciously, we make hundreds if not thousands of assumptions as we plan, budget and schedule these mega and giga scale projects. And because we do so, with rarely a second thought, our baselines might be best described as founded on a compounded uncertainty.

But rather than closely monitoring and tracking assumptions we allow them to propagate and migrate as the project proceeds, acting as “termites” that progressively further weaken our already uncertain foundations. How might our assumptions change and importantly, how might our management of large complex projects change if we simply wrote down all our assumptions and tracked their continuing validity throughout the project.

Assumptions are a fact of project execution but they require challenge by those who do not necessarily share the same reality. These assumptions pervade every aspect of project execution including the foundational theories of project management, developed in simpler times for simpler projects, but which we now treat as dogma. Until we are willing to challenge and revisit these foundational assumptions we will be held back from truly addressing the reality of large project execution – 2 out of 3 fail!

Assumptions are thoughts we take for granted and believe them to be true. They aren’t based on facts; they are based on experiences of the past. They are fiction. Assumptions inform our decision making, and this is precisely where the problem lies. They influence the decisions we make and often cause inertia.


Karla Reiss

As we approach the planning, scheduling and budgeting of large, complex projects we need to heed the spirit of Occam’s razor and make no more assumptions than are absolutely necessary. And in this parsimonious assumption set, as we write down our assumptions, made by tens or hundreds of individual actors, as a minimum let’s make sure they are internally consistent.

This paper lays out a framework for improving our treatment of assumption that can be summarized by the following figure, “Recommended Assumption Management Cycle”


Recommended Assumption Management Cycle


To read entire paper (click here)



About the Author

Bob Prieto

Chairman & CEO
Strategic Program Management LLC

Jupiter, Florida, USA




Bob Prieto is a senior executive effective in shaping and executing business strategy and a recognized leader within the infrastructure, engineering and construction industries. Currently Bob heads his own management consulting practice, Strategic Program Management LLC. He previously served as a senior vice president of Fluor, one of the largest engineering and construction companies in the world. He focuses on the development and delivery of large, complex projects worldwide and consults with owners across all market sectors in the development of programmatic delivery strategies. He is author of eight books including “Strategic Program Management”, “The Giga Factor: Program Management in the Engineering and Construction Industry”, “Application of Life Cycle Analysis in the Capital Assets Industry”, “Capital Efficiency: Pull All the Levers” and, most recently, “Theory of Management of Large Complex Projects” published by the Construction Management Association of America (CMAA) as well as over 570 other papers and presentations.

Bob is a member of the ASCE Industry Leaders Council, National Academy of Construction, a Fellow of the Construction Management Association of America and member of several university departmental and campus advisory boards. Bob served until 2006 as a U.S. presidential appointee to the Asia Pacific Economic Cooperation (APEC) Business Advisory Council (ABAC), working with U.S. and Asia-Pacific business leaders to shape the framework for trade and economic growth. He had previously served as both as Chairman of the Engineering and Construction Governors of the World Economic Forum and co-chair of the infrastructure task force formed after September 11th by the New York City Chamber of Commerce. Previously, he served as Chairman at Parsons Brinckerhoff (PB). 

Bob can be contacted at [email protected].