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The Triple Constraint Model Is It Time To Upgrade? Darrell G. Stiffler, Global Knowledge Instructor, PMP Introduction In the past, one of the key processes for a successful project was the solicitation of the customer and other stakeholder s flexibility of constraints in regards to project deliverables. Identifying the flexibility of the constraints associated with each deliverable was at least as important as identifying the deliverable. There appears to be a shift in this perspective with the release of A Guide to the Project Management Body of Knowledge (PMBOK Guide ) 4th Edition, which I will discuss later in this paper. Over the years, we have seen different models for managing stakeholder s preference in flexibility in regards to constraints. The PMBOK Guide historical models have been the Three Card Model and the Triple Constraint Model, which I discuss later in this paper. With the release of PMBOK Guide 4 th Edition, the two historical models are not mentioned. In the absence of a constraint model in the PMBOK Guide, I am proposing a new model based on other content from PMBOK Guide 4th Edition, which I have named the Stiffler Hexagon Constraint Model. A constraint as described by PMBOK Guide 4th Edition: The state, quality or sense of being restricted to a given course of action or inaction. An applicable restriction or limitation, either internal or external to a project, which will affect the performance of the project or a process. For example, a schedule constraint is any limitation or restraint placed on the project schedule that affects when a schedule activity can be scheduled and is usually in the form of fixed imposed dates. The Three-Card Model In the earlier days of project management, the project manager would sit down with a stakeholder and say, in regards to the project or deliverable, I have three cards Better, Faster, and Cheaper pick two. (Figure 1.) Better Faster Cheaper The purpose of this exercise was to help the stakeholder understand that it is not possible to deliver a project or deliverable with all three constraints remaining equal, and, therefore, choices have to be made. You can only have Figure 1. You can only have two cards. Copyright 2010 Global Knowledge Training LLC. All rights reserved. 2
If the stakeholder wants a deliverable to be Better and Faster, they want all the features and functions of the deliverable quickly completed. This means the project requires additional resources and extended working hours, and therefore, the deliverable cannot be considered Cheap. If the stakeholder wants the deliverable to be Better and Cheaper, no overtime or additional resources can be used, but the same amount of effort is required. The deliverable would take longer to reach completion and thus would not be Faster. If the stakeholder wants the project deliverable to be Cheaper and Faster, they will likely not get all the features and functions originally identified in the scope. Therefore, the project deliverable is not Better. The Triple Constraint Model: The 2000 edition of the PMBOK Guide states, Many project management practitioners refer to the project triple constraint as a framework for evaluating competing demands. The project triple constraint is often depicted as a triangle where each leg represents one of the constraints being managed by the project team. (See Figure 2.) It seemed odd that the Triple Constraint Model included four items, with, Time, and Cost () as the legs of the triangle and as the center of the triangle. The idea was to have the project manager sit down with the stakeholder and explain how the Triple Constraint Model affected the project or the deliverables and in some cases both. The message to the stakeholder was: if one of the three legs (, Time, Cost) of the model is changed (added to, or subtracted from), it would probably impact the other two legs and the central theme of. : If were added to or subtracted from, meaning if features and functions were added or reduced, it would either lengthen or shorten the Time needed to produce the project deliverable and increase or decrease Cost. It would probably affect in that if were increased and Time allotted remained the same, could possibly diminish because resources were stretched too thin to correctly complete all necessary tasks. Likewise, if were added to and Cost were not increased, there would not be sufficient money to pay for the resource s time. If were decreased and Time and Cost remained the same, there would be more than sufficient resources to pay attention to the deliverables, and could possibly be elevated. Time: If the Time allotted to produce the project or deliverable(s) were shortened or lengthened, Cost would increase or decrease. (features, functions or results) could possibly be reduced, removed, or added to, depending on the manipulation of Time. would be affected in that if Time were reduced and Cost remained the same, there would not be sufficient Time nor the necessary extra resources to focus on. If Time were lengthened and Cost remained the same, there would be more Time to focus on, which could then be elevated. Cost: If Cost were changed by an increase or decrease, the Time allowed to produce the project deliverable would probably shortened or lengthen. would probably decrease if Cost were decreased, and would probably be affected as suggested in previous paragraphs. Copyright 2010 Global Knowledge Training LLC. All rights reserved. 3
Figure 2 The Triple Constraint Model has served project managers well, and I suspect it will not disappear completely. However, as of the PMBOK Guide 4th Edition, the Triple Constraint Model is no longer referenced. On page 6 of the PMBOK Guide, it states: 1.3 What is Project Management?. Managing a project typically includes: Identifying requirements, Addressing various needs, concerns, and expectations of the stakeholders as the project is planned and carried out Balancing the competing project constraints including, but not limited to: Risk I must admit that I like the change; I have felt the triple constraint model to be woefully inadequate when discussing constraints with stakeholders. I have taken the new references to constraints in the PMBOK Guide and developed a new constraint model that consists of a hexagon node (see Figure 3) with each leg representing one of the six constraints named in the PMBOK Guide. The PMBOK Guide does not mention whether the order of the 6 constraints is significant; however, I believe the constraints should be listed in a specific order with equal consideration given to each one. The order should be,,,, Risk, and Copyright 2010 Global Knowledge Training LLC. All rights reserved. 4
. I have labeled the legs in priority order following a standard clockwise direction. In addition to labeling the legs of the hexagon, I added the words Customer Satisfaction to reinforce the idea that the setting of priorities of the constraints must be with the customer s approval and to their satisfaction. Figure 3 I have further illustrated the concept of the constraint model by creating a Work Breakdown Structure (WBS) using the new model (see Figure 4). I believe this illustrates a real life scenario of how a WBS works. From the Project and Phase level of a project, the Stiffler Hexagon Constraint Model WBS illustrates that key stakeholders must consider the impact of the six constraints. It further shows that on the deliverable level, should one of six constraints change and the other constraints not be reevaluated or one constraint be given more consideration, not only does the change affect the deliverable directly, but it affects the Phase as a whole. Therefore, it is imperative to give equal consideration to all six of the stated constraints. The elasticity of the triple constraint is still reflected in the new model. The PMBOK Guide states, The relationship among these factors is such that if any one factor changes, at least one other factor is likely to be affected. However, the PMBOK Guide is very specific in that the constraints should be balanced, not subjected to a either/or choices as reflected in the Three Card Model. Copyright 2010 Global Knowledge Training LLC. All rights reserved. 5
The model in Figure 4 illustrates how an equally balanced Stiffler Hexagon Constraint Model Work Breakdown Structure would appear. The beauty of the hexagon is that when all sides are equal the module fits nicely together, demonstrating a flawless solid cohesive model. Figure 4 The model in Figure 5 illustrates how the effect of not balancing the constraints would appear. Darrell G. Stiffler, PMP 10/16/09 Stiffler Hexagon Constraint Model Applied to a Work Breakdown Structure Project Project and s are subject to Customer Satisfaction Phase 1 Phase 2 Phase 3 Figure 5 Let s take a look at each of these constraints on an individual basis. Copyright 2010 Global Knowledge Training LLC. All rights reserved. 6
1. : It is my belief that should be the first constraint considered after the high-level description of the deliverable (product, service, or results) has been established. I have experienced situations where is almost an afterthought in project management, but I think most of us agree that should be the predominant consideration. It seems odd that a Project Manager s (PM) performance is measured by and compliance, when level of, as defined by the customer, is the primary concern of the customer. What good is a deliverable if it is not usable or durable? This is not to say that every deliverable has to be of the highest, but it must be at a level that is acceptable to the customer (meets or exceeds the customer requirement or specification). Not only should the of the deliverable be defined but also the of the resources to be used in the delivery of the deliverables. For example, the project may require equipment that can deliver a product with the ability to provide more accurate tolerance than equipment currently in use. 2. : Now that the of the deliverable has been established, the PM must define the deliverables and sub- deliverables necessary to produce the project deliverable. Not only must the required process to create the deliverable be defined, the activities necessary to produce the deliverables must also be addressed. Additionally, the competencies of the human needed to produce the deliverables at the level of desired must be defined. 3. : Building on the previous constraints, we have established the need and competencies of the to produce the deliverable. If exceptional for the project deliverables is required, using the standard model for budgeting may not be sufficient. For example, if it is standard practice for the performing organization to use the top-down methods in estimating, other methods may need to be considered. It may be necessary to use the Wideband Program Evaluation Review Technique (PERT) for greater accuracy. Because this project s expected exceeds normal, the Wideband PERT estimate will be a superior estimating tool. This constraint is only as good as the information and experience used to craft the document. 4. Resource: Resource refers to both human and capital. Close attention must be paid to the competencies of in-house. If a standard exceeds normal standards, the in-house may not be adequate and might require additional training or augmentation by outside. Similarly, capital assets must be scrutinized and evaluated to confirm that they have the capability to produce the level that is expected. The ability to garner the required within the budgetary constraints is generally one of the biggest challenges faced by the PM and other key stakeholders. It is at this point that there is usually a revisit to the level of,, and that was established. There will probably be compromises at this point, but don t forget to keep the constraints balanced. 5. : Assessment of must be made based upon the intended enforcement of all six of the defined constraints. Risk is based upon assumptions that constraint limitations have been accurately assessed. The PM, as well as other stakeholders, must identify possible Risk events associated with not only the 6 constraints in this model, but other possible constraints that may be identified due to the project s uniqueness. Probability and impact should be assessed on each identified, possible Risk. Once the probability and impact have been assessed and entered into the Risk Register, possible Triggers should be identified and a Risk response strategy crafted. Typically, the greatest are not outside the control of the PM. It is generally accepted that 85% to 90% of to a project can be identified prior to or during the planning stage of a project. Copyright 2010 Global Knowledge Training LLC. All rights reserved. 7
6. : Another big challenge for the PM is controlling the dealing with human nature and Mother Nature. This challenge is especially great when there is an elevation to the quality expectations of a unique project. The communicating of the expectations and crafting of the metrics ( must adhere to expectations and be measured by metrics) can be a daunting task. Adherence to is always complicated by the ability of human to focus on the task at hand. Duration estimates of activities use a complicated formula based on the resources competencies, availability, focus and, most importantly, attitude. The ability to predict a stakeholder s attitude and mental state in the future, however, is nearly impossible. The journey to emphasize and illustrate the importance of constraints identification in regard to a project deliverable continues. The more effectively and efficiently the PM and key stakeholders are able to balance the identified constraints, the better the chances the PM will be able to deliver a successful project. Past models have served our industry well. As we follow the path of progressive elaboration in the project management industry, we will discover or create more innovative means and tools to accomplish our goals. It is my hope that the Stiffler Hexagon Constraint Model will help students and practitioners of project management see the value of balancing all of the constraints on a project and execute better planning techniques. Please share your thoughts. You can find my e-mail address in my author bio. Learn More Learn more about how you can improve productivity, enhance efficiency, and sharpen your competitive edge. Check out the following Global Knowledge courses: Risk Management (PM04) and Cost Control (PM03) for Project Managers (PM06) For more information or to register, visit www.globalknowledge.com or call 1-866-925-7765 to speak with a sales representative. Our courses offer practical skills, exercises, and tips that you can immediately put to use. Our expert instructors draw upon their experiences to help you understand key concepts and how to apply them to your specific work situation. Choose from our more than 1,200 courses, delivered through Classrooms, e-learning, and On-site sessions, to meet your IT, project management, and professional skills training needs. About the Author Darrell G. Stiffler, PMP, has been a member of PMI since 1998 and received his PMP designation in September of 1999, a time when there were only 12,000 PMPs in the world. He is also certified in ITIL Foundations v2 & v3. He has over 20 years of project management experience in various industries with the preponderance of his experience in IT-related projects. He has consulted with both large and small organizations: General Motors; Xerox; Exel Logistic; VisionTek; Wellington Management; Boeing; General Dynamics. He has a military background and currently applies his years of experience to train and consult others in project management and ITIL professional development. He can be reached at DGStiffler@Verizon.net. Copyright 2010 Global Knowledge Training LLC. All rights reserved. 8