In the context of the PRINCE2 7 Plans practice, distinguishing between Tolerances and Constraints is fundamental to establishing realistic baselines and enabling 'Management by Exception'.
Constraints are restrictions or limitations within which the project must be delivered. They represent the no…In the context of the PRINCE2 7 Plans practice, distinguishing between Tolerances and Constraints is fundamental to establishing realistic baselines and enabling 'Management by Exception'.
Constraints are restrictions or limitations within which the project must be delivered. They represent the non-negotiable boundaries of a plan. Constraints effectively remove flexibility and are often driven by external factors or rigid business requirements. For example, a project might have a hard deadline due to new legislation (Time constraint), a fixed grant amount that cannot be exceeded (Cost constraint), or mandatory adherence to specific environmental standards (Sustainability constraint). During the planning process, constraints are identified first because the plan must be constructed to fit within these limitations.
Tolerances, conversely, define the permissible deviation from a plan’s specific target that is allowed before the deviation must be escalated to the next level of management. Tolerances provide the layer of autonomy required for the project management team to function without micromanagement. PRINCE2 7 establishes tolerances against seven aspects of performance: Benefits, Costs, Time, Quality, Scope, Risk, and Sustainability. For instance, a Stage Plan might have a target cost of $50,000 with a tolerance of plus/minus $5,000. As long as the stage is forecast to stay within $45,000 and $55,000, the Project Manager retains control. If the forecast exceeds these bounds, an Exception Report must be raised to the Project Board.
In summary, while constraints dictate the rigid parameters the plan must adhere to, tolerances define the authorized 'wiggle room' around targets, ensuring efficient governance and controlled progress.
Prince2 Practitioner v7: Master Guide to Tolerances and Constraints
Introduction to Tolerances and Constraints in the Plans Practice
In Prince2 v7, the Plans practice is essential for facilitating communication and control. Central to this control is the concept of Management by Exception. To manage by exception, specific boundaries must be set so that the management team knows when they have autonomy and when they must escalate an issue. These boundaries are defined by Tolerances and Constraints.
What are Constraints? Constraints are restrictions or limitations that the project is bound by. They are often binary (yes/no) or fixed points. Common examples include: - A fixed deadline date due to legislation. - A fixed budget cap that cannot be exceeded. - Specific quality standards that must be met for legal compliance.
What are Tolerances? Tolerances define the permissible deviation above and below a plan's target. They create a 'safe space' in which the Project Manager or Team Manager can work without bothering the level of management above them. If a forecast indicates that the work will stay within these bounds, the work continues. If the forecast indicates the work will go beyond these bounds (a deviation), an exception occurs.
The Six Aspects of Performance Tolerances can be applied to six specific aspects of project performance: 1. Time: +/- amounts of time on target dates. 2. Cost: +/- amounts of money on the budget. 3. Quality: Permissible ranges in quality criteria (e.g., a product weighing between 98g and 102g). 4. Scope: Permissible variation in the products delivered (e.g., 'must have' vs. 'should have'). 5. Risk: Limits on the aggregated risk exposure or individual threat impact. 6. Benefit: +/- ranges on the expected improvement (usually set at project level).
How it Works: The Hierarchy of Plans Prince2 relies on a hierarchy where authority flows down: - Corporate/Programme sets Project Tolerances for the Project Board. - Project Board sets Stage Tolerances for the Project Manager. - Project Manager sets Work Package Tolerances for the Team Manager.
If a manager forecasts that they will exceed their allocated tolerance, they must escalate to the level above immediately via an Exception Report (or an Issue regarding the Work Package).
Exam Tips: Answering Questions on Tolerances and Constraints
The Practitioner exam tests your ability to apply these concepts to a scenario. Here is how to approach these questions:
1. Identify the Level of Management: Determine who is taking action. If the question involves the Team Manager changing the scope, ask: Do they have the tolerance to do so? If a Project Manager is delaying a stage, check if the delay is within the Stage Tolerance set by the Board.
2. Distinguish Constraint vs. Tolerance: Look for specific wording. 'The budget is fixed at $50k' is a Constraint. 'The project can spend up to $55k or as little as $45k' describes a Tolerance. If a scenario says a deadline 'cannot be moved,' it is a constraint; if it says 'we can deliver a week late,' that implies a time tolerance.
3. Analyze the Exception Process: Questions often ask what a PM should do if a tolerance is threatened. The correct answer is usually to forecast the deviation and escalate (raise an Exception Report) rather than trying to fix it silently or waiting until the tolerance is actually breached. Remember: You escalate based on a forecast breach, not just an actual breach.
4. Check the Source of the Tolerance: Ensure you are looking at the correct plan. Project Plan tolerances apply to the whole project (Board responsibility). Stage Plan tolerances apply to the specific stage (PM responsibility). Do not confuse Project tolerances with Stage tolerances.