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Six Sigma



1. Definitions

  • A Method or set of Techniques, Six Sigma has also become a Movement focused on Business Process Improvement.

  • It is a Quality Measurement and Improvement Program originally developed by Mikel Harry and Richard Schroeder at Motorola in the early 1980's

  • It focuses on the Control of a Process to the Point of Six Sigma (standard deviations) from a centerline, or put another way, 3.4 defects per million items.

  • A Six Sigma systematic quality program provides businesses with the tools to improve the capability of their business processes. ...

  • It is a Business Process that allows companies to dramatically improve their bottom line by Designing and Monitoring everyday business activities in way that Minimizes Waste and Resources while Increasing Customer Satisfaction.

Mikel Harry

  • A Customer-Focused, Data-Driven Leadership Strategy

  • A Strategy - A Set of Tools - A Discipline - Leadership Development - A Common Language

GE Transportation
Aircraft Engines


  • The Six-Sigma process was developed at Motorola as a structured, closed-loop, team-oriented application of the scientific method.

  • This process was designed to assist teams in solving complex problems, using five steps in a sequential, closed-loop approach to improve process capability.

  • Process capability is measured in terms of sigma, which refers to the extent that the output of a process falls within its specification limits.

  • In statistical terms, sigma is a measure of variability, also known as standard deviation.

  • Achieving six-sigma means that a process has three standard deviations on either side of its mean value inside of the specification limits.

  • At that level, the process would be expected to produce only three defects per one million opportunities (the equivalent of having no "bad days during a lifetime, only a few "bad hours").

  • The process is commonly used at Motorola, General Electric, Allied Signal, and many other Fortune 500 companies.

  • The process is flexible within the 5 basic steps in that various improvement tools can be used at each step.


2. Six Sigma Fundamentals

  • Define What The Customer Wants

  • Measure The Key Output

  • Analyze The Data

  • Improve The Process

  • Control The Process



One sigma

170 misspelled words per page in a book

Two sigma

25 misspelled words per page in a book

Three sigma

1.5 misspelled words per page in a book

Four sigma

1 misspelled word 30 pages (about one chapter)

Five sigma

1 misspelled word set of encyclopedias

Six sigma

1 misspelled word in all the books in a small library


5. Why Do We Need Six Sigma?



3 Sigma 4 Sigma 5 Sigma 6 Sigma
1 93% 99.40% 99.98% 99.9997%
10 50% 94%


100 0.1% 54% 98% 99.97%
1,000 0% 0.2% 79% 99.7%
10,000 0% 0% 10% 97%
100,000 0%   0% 71%
  • Rolled yield: If there are 100 steps and each step is 99.4% good, the rolled yield is 54% good!

The more complex your process, the higher the required capability

6. Key Six Sigma Concepts

  1. Critical to quality 

    What the customer wants

  2. Defect

    Failing to deliver what the customer wants

  3. Process capability 

    What your process can deliver (entitlement)

  4. Variation  

    Everything varies

  5. Design for Six Sigma

    Designing to meet customer needs and process capability

Six  Sigma Quality and Productivity are Interdependent

7. The four fundamentals of Six Sigma

  1. Process …                 Everything Is Process

  2. Correlation …           Y f(x1, x2, x3)

  3. Discipline …             DMAIC

  4. Data …                     All Learning Resides In It

It Responds to Change By Driving Out Variation

8. The Focus of Six Sigma

To get results, should we focus our behavior on the Y or X ?



X1 . . . Xn


Key Process Output Variables


Key Process Input Variables




Input - process







If we are good at X why do we constantly test and inspect Y?


1. Define

Who are the Customers and what are their Priorities?

What is important to customer (CTQs)?

Define the “Y”


Identify the biggest Business Opportunities or Problems.

Select a Project to combat one important area.

Define Requirements

 Set Goal


Survey / Interview

• Quality Function Deployment QFD

• Process Mapping to find KPOV and KPIV

Risk Assessment FMEA

Financial Analysis


2. Measure

How is the process performing and how is it measured?

•  How is the process (The Y) performing for the customers (capability)?

•  How good could the process be (entitlement)?

•  How good is the data? Can I rely on it (gage R&R)?

Measure the “Y”


Validate Problem/ Process

Measure Key Problem KPOV’s

• Define Performance Standards for KPOV’s (Y’s).

Validate measurement for KPOV’s (Y’s).

• Measure Capability


Run Chart

Pareto Analysis

• Measurement System Analysis

Process Capability

Stratification Talk to the product to find out the location and repetitiveness of the defect

•  Gage R&R Gage Repeatability & Reproducibility


3. Analyze

What are the most important Causes of the defects?

What are the critical defects causing variation?
What % of variation?

Find & Measure the “Xs”


• Identify Vital Root Causes KPIV's

• Analyze the impact of these KPIV's on KPOV's

Prioritize KPIVs


Hypothesis Testing

Multivariate Charts

Fishbone Diagrams

Scatter Diagrams

FMEA Risk Analysis for Major KPIV's


Regression Analysis

Survey Analysis


4. Improve

How do we Remove the Causes of the defects?

How do we fix the critical defects (Xs)?

What % of variation in critical Xs can I remove?

Improve the “Xs”


Improve the vital few KPIV's.

• Establish Operating Tolerances on them.

• Measure Solution


• Design Of Experiments DOE

Sample sizes

Simulation Techniques

Risk Management

Error Proofing


5. Control

How can we maintain the improvements?

How can we maintain the improvements?

Control the “Xs” So Customer Never Sees Variation in the “Y”

Y = f(x1 , x2 , x3 …)


• Determine ability to Control the vital few KPIV's.

• Implement process control system on vital few KPIV's.

Standardize Solution


• Statistical Process Control SPC

• Failure Mode Effects Analysis  FMEA

• Push Leveraging

Action Plans


10. How do you implement Six Sigma

  • Leaders Must Own and Use It

  • Top Resources Selected into It

  • Projects Tied to Customer/Shareholder Bottom Lines

  • Business/Functions Manage with It Daily

  • Everyone Trains … Learns the Language

11. Get everyone involved in Six Sigma

  • Champions:

    Fully trained business leaders who own the processes and lead the deployment of Six Sigma in a significant area of the business

  • Master Black Belts MBB

    Fully-trained, full-time cross-functional quality leaders who team with champions and are jointly responsible for Six Sigma strategy, training, mentoring, deployment and results

  • Black Belts BB

    Fully-trained, full-time Six Sigma experts who lead improvement teams, work projects across functions in all areas of the business and mentor Green Belts

  • Green Belts GB

    Fully-trained individuals who use Six Sigma skills to complete projects in their job areas

  • Team Members

    Individuals who receive specific Six Sigma training and who support projects in their areas