What is Six Sigma?

Six Sigma is a methodology that provides an organisation with tools to improve business processes.

Motorola created Six Sigma as a method to provide their organisation with tools to improve the capability of their business processes. This increase in performance and decrease in process variation lead to defect reduction and improvement in profits, employee morale, and quality of products or services. Six Sigma quality is a term generally used to indicate a process is well controlled (within process limits ±3s from the centre line in a control chart, and requirements/tolerance limits ±6s from the centre line).

Six Sigma is a methodology and toolset originating in Japan (Motorola) applied for the purpose of improving businesses processes. As a result, it focuses on finding and removing faults or potential variation in a system. Six Sigma is a structured sequence of steps employing quality management methods to complete specific goals such as:

  • Reduce process cycle time
  • Decrease in pollution
  • Reduce costs
  • Increase customer satisfaction
  • Increase profits

The Six Sigma Rating

Unlike other process improvement methodologies, the capability of Six Sigma has a grading system known as the sigma rating. The sigma rating indicates how frequently a product defects and how much is yielded from the process. Motorola set a goal to reach Six Sigma in all of their manufacturing processes or a 99.99966% chance to be free of defects (3.4 defective features per million opportunities). During Motorola’s attempt at reaching the rating of Six Sigma they began to refer to the management and engineering practices used to achieve it also as Six Sigma.

Since every organisation is different experts do not always agree on which tools are mandatory or complete the set. However, there are many statistical and graphical tools that are mentioned in these discussions time and time again. Due to that, we’ve listed what we feel are the primary tools to reach the Six Sigma rating below.

Firstly, identifying problems, opportunities to improve and requirements:

  • Project charter – Clarify the target, scope, course, and motive for the improvement team.
  • Voice of the customer – Receive and understand feedback from current and future customers to learn what satisfies, delights, and dissatisfies them.
  • Value stream map – Analyse what is needed to meet those customer needs using an overview of an entire process from start to finish.

Measuring process performance:

  • Process documentation – Record the activities, decisions and events which make up a process.
  • Capability analysis – Assess whether a process meets expectations to satisfy customers, produce faultless products or provide a quality service.
  • Pareto chart – Analyse the frequency of defects and their causes.

Analysing processes to determine root causes of variation, defects, or poor performance:

  • Root cause analysis – Identify what is producing issues.
  • Failure mode and effects analysis – Distinguish possible product, service, and process failures
  • Multi-vari chart – Detect variation within a process

Improving process performance by addressing root causes:

  • Design of experiments (DOE) – Find solutions to issues with complex systems and processes.
  • Kaizen event – Focus on a narrow project using ideas from the people who actually do the work for rapid change.

Finally, controlling the improved process and future performance:

  • Control plan – Document necessary actions to improve processes continuously.
  • Statistical process control (SPC) – monitor process behaviour
  • 5S – Build a workplace designed for visual control
  • Mistake proofing (poka-yoke) – Reduce errors by making them immediately detectable or impossible to occur.

Additionally, Six Sigma team leaders often use project management tools such as Gantt charts and team engagement tools like brainstorming and nominal group technique. In conclusion, Six Sigma provides a massive boost to an organisations performance when integrated fluidly.

Source: ASQ, Learn about Quality, What is Six Sigma