What is Six Sigma – quality control tools and methods

When a business is firmly established, a common method used to optimise the business is to apply various techniques used in the Six Sigma methodology.

Six Sigma is about understanding the effectiveness and yield of a business process, by measuring issues and defects.

Then, using a set of tools, techniques and methods, you can resolve issues, eliminate waste, reduce defects, optimise profits and improve customer experience.

Usual applications

Six Sigma is best suited to manufacturing and retailing industries where ‘real defects’ can occur during product manufacturing, but has more recently been applied to professional industries and corporations also who are looking to reduce waste, effort and defects for processes and procedures relating to customer experience – it’s all about Quality Management.

Key differences

Six Sigma is all about quality control and continuous improvement, improving profitability and productivity to reduce, eliminate and resolve defects and waste in products or services.

Six Sigma is often compared against Human Centred Design which rather applies a customer-centric approach to problem solving and focuses on the experience, rather than profitability and productivity.

  • Six Sigma: Continuous improvement and optimisation for existing experiences.
    Improve 100 products or processes by 1%
  • Human Centred Design: Using empathy to design or redesign new experiences.
    Improve 1 product or service by 100%

What does it mean?

Six Sigma is all about achieving the highest-standard in quality which is a maximum tolerable 3.4 defects per one million products or service processes.

A ‘defect’ according to Six Sigma is anything that from a customer’s perspective is not acceptable and means the customer will need to contact the organisation again to either fix the issue, arrange a refund or arrange a repair.

Sigma Level Defects Per Million Opportunities (DPMO)
1 690,000
2 308,537
3 66,807
4 6,210
5 233
6 3.4

Common methods

  • DMAIC – Define, Measure, Analyse, Implement, Control
  • The 5 whys
  • Correlation analysis
  • Cost-benefit analysis
  • Critical-to-Quality (CTQ) diagrams
  • Cause-and-effect (Ishikawa) diagrams
  • Quality Function Deployment (QFD)
  • Defects per million opportunities (DPMO)
  • Value Stream Mapping
  • Root-cause analysis
  • Pareto charts
  • Control charts

Definition

noun

Six Sigma (6σ, Lean Six Sigma): a set of management techniques intended to improve business processes by greatly reducing the probability that an error or defect will occur.

Benefits

  • Improved quality control resulting in fewer defects, less product returns, etc
  • Investigates and resolves issues with manufacturing or service processes
  • Takes a proactive approach to improving business performance

Disadvantages

  • Focussed on productivity or profit primarily for existing products or services
  • Usually involves continuous improvement only, not experience redesign

Do you use Six Sigma in your workplace? What has worked, what hasn’t? Let us know in the comments below.