Article - Break Down Structures - WBS OBS RBS PBS CBS an Overview

Break Down Structures – An Overview

Types of Break Down Structures

• WBS (Work break Down Structure)
• OBS (Organizational Break Down Structure)
• RBS (Resource Break Down Structure
• PBS (Product Break Down Structure)
• RBS (Risk Break Down Structure)
• CBS (Cost Break Down Structure

 Details

A work breakdown structure (WBS) in project management and systems engineering, is a tool used to define and group a project's discrete work elements (or tasks) in a way that helps organize and define the total work scope of the project

A work breakdown structure element may be a product, data, a service, or any combination. A WBS also provides the necessary framework for detailed cost estimating and control along with providing guidance for schedule development and control. Additionally the WBS is a dynamic tool and can be revised and updated as needed by the project manager.

In project management, a product breakdown structure (PBS) is an exhaustive, hierarchical tree structure of components that make up an item, arranged in whole-part relationship.

A PBS can help clarify what is to be delivered by the project and can help build a work breakdown structure.

The PRINCE2 project management method mandates the use of product based planning, part of which is developing a product breakdown structure.

PBS of a computer (example):

• Main unit
  • Housing
  • Motherboard
    • CPU
    • RAM chips
    • ...
  • FDD
  • HDD
  • Video card
  • Sound card
  • Network card
  • LPT port card
• Monitor
  • CRT
  • Housing
  • Electronic components
• Mouse
  • Body
  • Marble
  • Cable
• Keyboard

What is a "Risk Breakdown Structure?"

To better grasp when the project needs to receive special scrutiny, in other words, when risk might happen, a simple tool, the RBS, will prove extremely valuable. The RBS can also help the project manager and the risk manager better understand recurring risks, and concentrations of risk which would lead to issues that affect the status of the project.

Following the concept of the Work Breakdown Structure,  the Risk Breakdown Structure provides a means for the project manager and risk manager to provide a means of structuring the risks being addressed and/or tracked. Just as PMI defines the Work Breakdown Structure as a "deliverable-oriented grouping of project elements that organizes and defines the total work scope of the project..." the RBS could be considered as a "a hierarchically organized depiction of the identified project risks arranged by risk category.

 Many project managers and risk managers currently use "home-grown" methods for listing, identifying, assessing, and tracking risks in their projects. These methods include spread-sheets, listing, generic risk taxonomy, based somewhat loosely on various standards and guidelines.

Simply putting the risks in a list or a simple table or even in a database does not provide the strength of using a structured, organized method similar to a Work Breakdown Structure. To fully understand the risks and therefore to better identify and assess the risk, a "deep-dive" into each risk taking as many levels of identification as necessary may be required. The project value of placing risks in a structure such as this lies in the ability of the project manager and risk manager to then quickly and easily identify and assess the risk, identify the potential risk triggers and develop a more robust risk response plan   If all risks are placed in a hierarchical structure as they are identified, and the structure is organized by source, the total risk exposure to the project can be more easily understood, and planning for the risk more easily accomplished.

Cost breakdown structure (CBS)

Classification of costs within a company or project into cost units/cost centers and cost elements/cost types. The establishment of a cost structure aids efficient cost planning, controlling, and the introduction of measures to reduce costs