The Analyze phase in DMAIC aims to find the root cause for the variation in our process. Sometimes, the culprits are simple to find. Sometimes, the culprits are easy to identify. How do you create a hypothesis about what is causing the variation? Six Sigma describes process variation using 6M’s (aka five M’s or one P). These six elements contribute to variation within a process. These six elements, 5 Ms and 6 M’s of six sigma have an influence on the variation in all processes, manufacturing or not.

Ishikawa refers to the 6 M’s of six sigma, also known as the 5Ms and the 1P as Man, Machine Material Method, Measurement, Mother Natura

  1. Method
  2. Mother Nature’s “Environmental”.
  3. (Man) People
  4. Measuring
  5. Machine
  6. Materials

Manufacturing Example: 6 M’s

  1. Method
    • An assembly line is very different from a manufacturing floor.
  2. Mother Nature’s “Environmental”.
    • Machines may be more susceptible to breakdowns due to ambient humidity than normal.
  3. (Man) People
    • Allowing an individual employee to stop production if he discovers a defect.
  4. Measuring
    • Problems could arise if the supplier measures in English units while the manufacturer measures using metrics.
  5. Machine
    • The machine’s age and strength may have an impact on the process.
  6. Materials
    • Certain materials are more difficult to work with than others.

6 M’s of Six Sigma in Management

  1. Method
    • Each method can be different, even if one team uses a Waterfall approach to software development and another follows an Agile process.
  2. Mother Nature’s “Environmental”.
    • The north has more tolerance for snow days than the south.
  3. (Man) People
    • Untrained in 6 Sigma tends to concentrate on the “Man” portion of the 6Ms rather than the process itself.
    • Unenlightened managers will most likely focus on Man if they are not proficient in six-sigma. Managers who aren’t enlightened in six sigma tend to see the process performance more as influenced by the person component, than the five Ms of the machine material, method, measurement, or mother nature. Don’t ask who, ask why.
  4. Measuring
    • If each team leader rewards different behaviors, it can be difficult to judge teams equally.
  5. Machine
    • Software developers may have lower productivity if they use slower computers or less efficient tools.
  6. Materials
    • Only the raw materials that employees have access to can make a product as good or better than what they build.

6M Insights

  • A bell-shaped curve is not affected by any of the five Ms or oneP.
  • Six elements are responsible for variation in a process. These six elements, 5 Ms and 6Ms (or 6Ms) influence the variation in any manufacturing process.
  • The 6M approach could be used as a spine for each fishbone diagram, and then asks the 5 whys in order to narrow down the root cause.

You can use the 6Ms or similar variations to help you categorize process inputs. The 6Ms can be used to identify and fix process problems or variations. You can use it in many functional areas across multiple applications.

You might see the term “Milieu”, instead of Mother Nature, in some versions of the 6Ms. The 6Ms are a good way to recall the process elements. However, you’ll often see the 6Ms as 3Ms 2Es, and 1P. These represent Method, Equipment Material, People, and Measurement. You might also see the 5Ms, 1P, and Mother Nature where Machinery and Mother Nature are kept. However, Manpower is People. Despite all the confusion and differences in terms, the concepts and elements remain consistent.

The 5Ms will be used where Mother Nature has been dropped. The 6Ms in Marketing could be described as Media, Market, Media, Money, and Manage. The 8Ms version might include Management and Maintenance.

The Fishbone diagram is most commonly used in manufacturing environments. However, root cause analysis can also be applied to non-manufacturing or transactional processes. Machinery and Material might not be as relevant to non-manufacturing processes, so you may see People, Policies, and Processes as the primary bones of the Fishbone Diagram.

No matter what words are used to describe the process elements or the method of searching for root causes, the approach and methodology remain the same.

The 6 M’s of six sigma have 3 benefits

This is a very useful approach because of its simplicity.

It provides a framework

Brainstorming is one of the first steps in creating a Fishbone Diagram. The 6Ms are the context and format for your brainstorming.


You may find yourself focusing on topics or discussions that aren’t relevant to the root cause of the problem during a root cause analysis. You can use the 6Ms to help you keep your discussion focused and on track.

Allows for a deeper dive

It is crucial to continue asking the question, “What causes that?” when doing root cause analysis. This is the key to finding the root cause. You can increase your chances of finding the root cause by drilling under each M.

What are the 6 Ms?

Root cause analysis is most commonly done using the 6Ms. You will need to be able to read and understand the meanings of each M to properly use a Fishbone Diagram.

1. Root cause analysis is based on a foundation

When doing root cause analysis using a Fishbone diagram or Ishikawa diagram, the 6 Ms are the most frequently used terms.

2. This broad perspective provides a wide view

A combination of factors could be the root cause of a problem in a process. You can use all six Ms to analyze the possible causes of a process problem.

3. Simplicity in use

The 6Ms are able to take complex problems and break them down into smaller categories that make it easier for you to understand the relationships between process inputs, and variables.