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What is a WBS Dictionary and Why You Need One

WBS Dictionary Definition

Defining a project scope is an essential to success at any project. It ensures that project deliverables and all other project requirements are clear enough and well defined.

One of Project Scope component is WBS dictionary. It helps identifying and describing each work package (the lowest level of WBS) exists at the Work Breakdown Structure (WBS). As shown in figure#1, all Work packages are represented as names only. This doesn’t give the sufficient details of these deliverables. Project stakeholders need to communicate among the project with enough and complete information about each deliverable. That information can be found at WBS Dictionary.

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Figure 1: WBS of an Architectural Design Project

WBS Dictionary Role

Maintaining WBS Dictionary in a project would provide useful details and information about project work packages. This information would enhance the communication process between projects stakeholders, and consequently this would prevent scope creep (additional scope or uncontrolled change in project scope) as a result of insufficient project scope definition.

WBS Dictionary Elements

WBS Dictionary documents the information about work package. It has several fields about each work package. Such as:

  • Description: a narrative statement about the work to be done.
  • Assumption: circumstances or events that need to occur for a project to be successful.
  • Constraint: factors that might limit or restrict this work package, such as Timeframe or Budget.
  • Duration: the amount of time required to accomplish this work package.
  • Predecessors & Successors: these reflect the interdependencies of the work package by showing the previous work package (Predecessors) and the next work package (Successors).
  • Start and Finish date: the expected start and finish date of a work package as a result of the scheduling process.
  • Author (individual/organization): the person/project team in charge of carrying out the work package.

WBS Dictionary Elements

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Figure 2: WBS Dictionary Example

Ultimately, for each work package that exists in our WBS, we should maintain a corresponding WBS Dictionary. So it will have the sufficient information of our WBS.

WBS Dictionary & Planning Process

Developing WBS dictionary in a project reflects an advance project management practice for this project. Although WBS and its components (Work packages, WBS dictionaries) are developed at the early stage of a project (in the defining of the project scope process), WBS dictionary represents some projects details coming from different project management outputs like: Cost Management, Time Management, HR Management …etc. which supposed to be carried out after the Project Scope Management.

This means that WBS Dictionary is a result of iteration techniques at the planning process. At the beginning of a project where the details are not yet clear at this time, Project Management Team develop the initial version of WBS Dictionary. Then at later stage, they should revisit the outputs of the planning phase and try to modify it and update it based on the available new information.