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Work Breakdown Structure (WBS)

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The Work Breakdown Structure (WBS) is a foundational tool in project management that decomposes a project into smaller, more manageable components. It represents a hierarchical decomposition of the total scope of work to be carried out by the project team. By breaking down the project into discrete elements, the WBS facilitates better planning, scheduling, budgeting, and control. In the context of scheduling, the WBS serves as the backbone for defining project activities. Each component of the WBS can be further detailed into tasks and subtasks, which are essential for developing a comprehensive project schedule. The WBS ensures that all work required for the project is identified and that there is a clear understanding of how each task contributes to the project's objectives. Creating a WBS involves several steps. First, the project scope is defined, outlining all deliverables and objectives. Next, the project is divided into major deliverables or phases. These are then successively broken down into smaller components, such as work packages or activities, until a level of detail is reached that is suitable for scheduling and control. The benefits of utilizing a WBS in scheduling are numerous. It enhances clarity by providing a visual representation of the project's scope and tasks. This clarity helps in assigning responsibilities, estimating durations and resources, and identifying potential risks. Additionally, the WBS aids in preventing scope creep by ensuring that only the defined work is included in the schedule. Overall, the Work Breakdown Structure is an indispensable tool for project managers. It lays the groundwork for effective scheduling by organizing and defining the total scope of the project. By systematically breaking down the work, the WBS contributes to more accurate scheduling, better resource allocation, and improved project control.

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PMI-SP - Project Management Basics for Scheduling Example Questions

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Question 1

In a Work Breakdown Structure (WBS), what is the purpose of the 'Rolling Wave Planning' approach?

Correct Answer: To progressively elaborate work packages as more detailed information becomes available

Rolling Wave Planning is a key project management technique where detailed planning is done on a progressive basis. The correct answer reflects the core principle of Rolling Wave Planning - work packages are elaborated progressively as more information becomes available during project execution. This approach recognizes that early in a project, not all details may be known, and planning becomes more detailed as the project advances. The other options are incorrect because: - Creating a comprehensive schedule baseline at project initiation contradicts the iterative nature of Rolling Wave Planning - Sequencing work packages based on dependencies is part of general scheduling but not specific to Rolling Wave Planning - Creating parallel work streams is a general execution strategy and not related to the progressive elaboration aspect of Rolling Wave Planning Rolling Wave Planning specifically addresses the reality that future work packages may start with high-level information and become more detailed as the project progresses and uncertainty decreases.

Question 2

What is a primary characteristic of a well-constructed Work Breakdown Structure (WBS)?

Correct Answer: It follows the 100% rule for project scope inclusion

The 100% rule is a fundamental principle of WBS construction stating that the WBS must include 100% of the work defined by the project scope and capture ALL deliverables (internal, external, interim) related to the project. This characteristic ensures that all project work is accounted for and there are no gaps in the project scope definition. The other options are incorrect because: Predetermined six-week intervals are not a WBS characteristic - this is an arbitrary timeframe that may not suit all projects. Organizing by sequential order of completion dates is not a WBS feature - the WBS is about decomposition of scope, not scheduling. Establishing dependencies and resource assignments happens during schedule development, not during WBS creation. The WBS focuses on deliverables and scope decomposition.

Question 3

When decomposing work packages in a WBS, what is the '100% rule'?

Correct Answer: The sum of work at each level must equal the total work above it

The 100% rule is a fundamental principle in Work Breakdown Structure (WBS) creation stating that the sum of all child elements at any level must equal the work represented in the parent element above it. This rule ensures: - Complete scope coverage - No work is counted twice - All project work is captured - Proper hierarchical decomposition Why other answers are incorrect: Resource allocation (team member time) is not related to the 100% rule - this is a scope planning concept, not a resource management one. Project closure requirements are not related to the 100% rule - this is about work decomposition, not completion status. The 100 hours requirement is arbitrary and incorrect - the rule applies to scope decomposition, not time estimates.

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