Project Management: Work Breakdown Structure

Work Breakdown Structure (WBS)

• A WBS is a deliverable-oriented hierarchical decomposition of work.
• It's used by project teams to achieve project objectives and create deliverables.

Goals of the Unit

• Understand the transition from project goals to the project schedule.
• Introduce WBS notation.

WBS Structure and Process

• The WBS is part of the project planning phase.
• The WBS is used with other project management areas like change control.
• Sequential tasks are connected to each other. A starting point and finishing point are defined and the tasks are connected.
• The process includes steps like initiating, planning, executing, & closing.

WBS Format and Components

• Two formats exist: graphical (tree diagrams in programs like Vision, Graffle, and LibreOffice) and textual (MS Word, Text Editor, and Outliners).
• A decimal numbering system is used to identify elements (e.g., 3.1.5).
• "Is contained in" relationships are shown.
• Dependencies and durations are not shown in the WBS.

Why is a WBS Useful?

• Establishes the basis for defining project work.
• Shows how tasks/activities relate to project objectives.
• Creates a framework for defining, assigning, and monitoring work and costs.
• Identifies the organizational units responsible for completing project work.

WBS Rules of Thumb

• Everything (and nothing else): All required work items should be included and no unnecessary items should be present. The 100% rule applies to ensure comprehensive item coverage. The Mutually Exclusive rule means tasks shouldn't overlap.
• Balanced Paths: Not required; not all paths need to be the same level.
• High Quality WBS:
• Coherence: Tasks within work packages should share the same goal.
• Coupling: Minimize task dependencies between work packages.
• Continuity: Work packages should be full-time to maximize efficiency.
• Cost: Work packages should require effort between one person-week and one person-month.

Stopping Point in Constructing a WBS

• Work package level is the standard stopping point.
• Note: individual work packages may contain more elementary activities.
• The size of a work package will depend on project size:
• NASA/DOD PERT Cost standard: Work package duration is no more than 3 months of effort or $100,000.
• Other standards: approximately 1-2 weeks of effort or 1-2 people capacity.

WBS Types

• Product: Based on the structure of required outputs. It can start from a Product Breakdown Structure.

• Process: Based on the project phases (e.g., Requirements, Analysis, Design, Testing).

• Hybrid: Combines the product and process approaches.

• Organizational WBS/Geographical WBS: Higher levels represent organizational units/geographically distributed teams; lower levels define task responsibilities at the unit or team level.

• Program WBS (PWBS): Used to coordinate projects within a larger program.

• Contract WBS (CWBS): Used as the basis for subcontracting work/system development. Commonly used by NASA.

WBS Dictionary

• A WBS dictionary provides more details on each WBS item.
• Typical information included includes: detailed descriptions, work quantities, and contractual elements.
• Rules of thumb include that all entries could have additional entries, details increasing as you move from upper to lower levels of the tree. A best practice is to ensure work packages are completed as described in the Dictionary.