Six Constraints: An Enhanced Model for Project Control – Introduction (#1 in the series Six Constraints: An Enhanced Model for Project Control)
By Jay Siegelaub – MBA, PMP, PRINCE2
For many years project managers have been encouraged to look to the Triple Constraints to provide a framework to plan, monitor and control a project. In its Glossary, A Guide to the Project Management Body of Knowledge (PMBOK Guide)® defines the Triple Constraint as “a framework for evaluating competing demands.” These Triple Constraints (time, cost and scope, with quality occasionally included as an adjunct to or substitute for scope, or as a fourth constraint) indicated the key factors that both defined the framework of a project, and directed project managers as to where adjustments would have to be made if one or another of those constraints became problematic.
You could only request two of the three, and the third factor would get defined by the first two. The shorthand version of this model said “cheap, fast or good – choose two”. If you want to have it cheap (low cost), and fast (short time frame), you would have to settle for limited scope or lower quality. If you wanted it fast and good (high quality with full scope), then it would cost you. We also understood that if the project was expected to run longer than planned, to bring it back into the desired time frame would require a compromise on either cost (i.e., spend more money to get it done on time) or scope/quality (reduce the scope, or settle for lower quality in the form of reduced characteristics, or less quality checking).
In recent years there has been greater understanding of the factors impacting on a project; PRINCE2™ has identified these revised factors through its focus on Tolerances. While building on the core factors of time, cost and scope, PRINCE2™ has added quality (as a distinct factor), along with benefits and risk – to produce six constraints.
PRINCE2™ employs “tolerances” – its term for these six constraints – as key project controls. They are dimensions of the project for which ranges of acceptability are defined, which are monitored to identify or anticipate when a plan has entered “problematic” or “exception” territory. They are needed and used at all three planning levels of a project – the project as a whole, any one stage or phase of the project, and at the detail work package level.
This paper will first define what each of these six constraint factors means, in both theoretical and practical terms. It will then discuss how to use them during a project, and finally, locate them in the PMBOK® Guide.
The Six Constraints (to be discussed in details in later articles)
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.