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Where the Six Constraint model fits into the PMBOK® Guide
(#7 in the series Six Constraints: An Enhanced Model for Project Control)
By Jay Siegelaub – MBA, PMP, PRINCE2

Even though it defines the Triple Constraint as “a framework for “evaluating competing demands,” the PMBOK® Guide makes no specific reference as to how or when to apply the Triple Constraint to do just that.

It is clear, though, that application of the constraints/ tolerances occurs in 2 key points in the PMBOK® Guide’s process flow. The first is in planning, where we have to assess:

  • what the constraints/ tolerances should be (if they have not been previously defined);
  • who should be setting them (and when);
  • how they are to be used by the project manager;
  • how the sponsor/ stakeholders/ Project Board will be kept informed of the status of the constraints and project.

The second area is in monitoring/ control, where consideration needs to be given to:

  • determining what is going on in the project (standard data collection/ monitoring processes);
  • assessing how that compares against the constraints/ tolerances the sponsor/ stakeholders/ Project Board have agreed to with the project manager;
  • whether any of the constraints/ tolerances been breeched – or threaten to be breeched; (PRINCE2™ emphasizes the importance of dealing with tolerance/ constraint breeches as soon as they are forecasted, rather than waiting for them to occur, so there are more options – and time – to deal with the situation.)
  • proposing and recommending alternatives for addressing the breech.

The planning and setting of constraints/ tolerances should occur in each of the respective knowledge areas addressed by them: time (schedule, chapter 6), cost (chapter 7), risk (chapter 11), scope (chapter 5) and quality (chapter 8). Although benefits are not specifically identified in the PMBOK® Guide, they normally would be included in the Business Case section of the Project Charter (in Initiating, The PMBOK® Guide does not make provision for regularly referencing the Business Case in the course of the project, so any ongoing use of benefits and the Business Case in assessing project viability will need to be added through the use of the required project management methodology (as specified in (See below how the use of the PRINCE2™ project management methodology will assist in this.) How the constraints/ tolerances are to be used by the project manager and stakeholders/ Project Board needs to be part of the Project Management Plan, under each of the ‘management plan’ sections (schedule, cost, etc.), as well as change control, issue management and communications.

The day-to-day monitoring and control of the constraints occurs in “4.5 Monitor and Control Project Work,” where the key Tools/ Techniques (4.5.2) are: “ Project Management Methodology,” “ Project Management Information System” and “ Expert Judgment.” Your “expert judgment” now includes the understanding gained here about the value of using all six of these constraints to track the project’s progress. It is also used to determine when the project is in trouble – ie, when one or more of the six constraints has exceeded, or is anticipated to exceed its limits, as agreed between the sponsor/ stakeholders/ Project Board and the project manager.

PRINCE2™ – a respected and widely used project management methodology – can largely fulfill the requirements of “ Monitor and Control Project Work: Tools and Techniques – Project Management Methodology”. PRINCE2™ defines and manages all six constraints/ tolerances during the project. It additionally addresses the Business Case by identifying its contents (including benefits) and the points during the project when the Business Case needs to examined, updated and evaluated, and proposes a Project Board to clearly define the sponsor’s role and responsibilities.

Next Steps

The next time you work on a project – or observe a project others are working on – think about these six constraints. Consider the assumptions and the decisions that are made about the six without their being discussed. Think, then, about how a clear discussion of these six constraints would allow better control of the project’s key elements from all perspectives. Then think about how you can use them to manage your projects better.
To remember the Six Constraints, think “CRaB QueST” (Cost, Risk, Benefits, Quality, Scope and Time).

Jay Siegelaub has over 30 years of professional experience delivering and supporting projects in information technology, insurance systems, banking, and nonprofit strategic planning, as well as in the pharmaceutical, financial service, consulting, and consumer products industries. As a recognized educator he has trained thousands of project managers over the past 23 years, including 13 years as the Project Management tutorial instructor for the Drug Information Association.

Jay’s recent responsibilities included leading the North American Change Management and Training practices for a UK-based management consulting firm, training corporate consulting professionals in project and program management, and supporting clients in managing the “people” issues of their business change initiatives. He has authored articles on training, project management and information technology for various publications, and often presents at conferences, including the PMI North American Congress (1999, and 2004 – 2007), ProjectWorld and ProjectSummit.

In addition to his PMP® certification, Jay has his MBA in Organization Management from New York University’s Stern School of Business, and is an accredited PRINCE2™ Practitioner, Instructor and Examiner. He has taught and consulted in PRINCE2™ in North America for 10 years (the first US-accredited PRINCE2™ instructor), and worked for the company (and with the authors) that wrote the PRINCE2™ Manual for the UK government.

He has provided Change Management and Project Management consulting and training (including PRINCE2) to companies such as Sun Microsystems, NATO, the United Nations Development Programme, Bechtel, IBM, Philip Morris, Credit Suisse, JPMorganChase and Diageo.

Jay also consults in Organizational and Professional Development.

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