Welcome to the Six Sigma Line! This series of blog articles addresses topics that we find interesting and provides potentially useful information to anyone trying to enhance their business skills.

Six sigma principles include the following:

  • Customer focus
  • Use of teams that are assigned well-defined projects that have direct impact on the organization’s bottom line
  • Using statistics at all levels
  • DMAIC approach (define, measure, analyze, improve and control) to problem solving
  • A management environment that supports these initiatives as a business strategy.

Today, let’s look at the fourth principle: DMAIC, or The Six Sigma Way.

Six Sigma projects follow methodologies derived from Walter Shewhart and W. Edward Deming’s Plan-Do-Check-Act cycle. This evolved into the DMAIC method, which has five critical phases:

  1. Define the problem
  2. Measure to gather data that describes the current situation
  3. Analyze (Root Cause Analysis)
  4. Improve by choosing and implementing solutions
  5. Control to standardize and sustain the solution

We can further divide the five phases into 13 steps:


D1 Select an Output Characteristic What are we improving?
D2 Define Output Performance Standards What is the standard, or the goal?
D3 Describe the Process Do we understand everything about the process in question?


M1 Validate the Measuring System Can we trust the data?
M2 Gather Data to Establish the Baseline How bad is it? Or… is it better than we think?
M3 Validate Project Objectives Now that we know our baseline, is our standard realistic? Will it pass the RUMBA test (we’ll explore that more in a future post)?


A1 Identify Potential Causes Gather up as many suspects as possible.
A2 Screen Potential Causes Screen the suspects down to a manageable number that may be tested.
A3 Determine the Root Cause Choose the most likely to test and confirm.


I1 Identify Solution(s) Select the best solutions.
I2 Re-evaluate the Measuring System Can you still trust the data?
I3 Gather Data to Document the Improvements How much did we improve?


C1 Sustain and Spread Implement controls to maintain the gains (no backsliding), and see if the improvements can be applied to other areas.

Every organization is different and projects vary from company to company. As such, not every one of the steps above will apply to every project.

However, if you decide to omit a step, make sure that the team agrees that the step isn’t applicable. Be sure to note this on your project charter and describe the reasoning behind the omission.

Remember that the best way to become competent in the Six Sigma Way is through repetition.

“Tell me and I forget, teach me and I may remember, involve me and I learn.”

Benjamin Franklin

About Purdue’s Online Lean Six Sigma (LSS) Certificate Program

Purdue University offers comprehensive online Lean Six Sigma (LSS) certificate programs designed for working professionals with varying levels of Lean Six Sigma experience. The online Lean Six Sigma certificate courses prepare professionals to satisfy the immense demand for Lean expertise, skills and certification.

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