Page 423 - Six Sigma Demystified

Part 3 S i x S i g m a To o l S 403

Work breakdown Structure

A work breakdown structure (WBS) is a tree diagram used to break down
problems or projects into their components. It reduces “big and complex”
issues down to “tiny and manageable” issues that a single project can ad-
dress.
By breaking the process down into its components, we can recognize that
there are really several subprocesses that would each require separate improve-
ment strategies. Limiting our project to one or only a few closely related catego-
ries will lead to a better chance of project success. We will need to understand
the potentials for each of these subprocesses in financial terms to justify a given
project proposal.

When to Use

Define Stage

• To categorize the problems so that the project can focus on one or more
key areas (used in conjunction with Pareto analysis)

• To reduce the scope of the project to ensure completion in a reasonable
time frame

Analyze Stage

• To break down a problem into its potential components to be addressed
in the improve stage.

Methodology

At each level of the tree, brainstorm on categories for each element: How many
different ways can this element occur? For example, a project was developed to
reduce the cycle time for a purchase order. A work breakdown structure was
used to understand the process dynamics. In this case, the process can be broken
down into approved and unapproved vendors and then by classification of the
purchased items.