image
Simon Buehring

Six Sigma

Six Sigma offers tools for improving business processes and quality. Read on to see how it can benefit your projects.
Six Sigma
Contents

Introduction

You may have heard of Six Sigma and Lean Six Sigma. These two approaches are complementary, so much so that the terms are often used interchangeably. They also have some notable differences. Understanding how they differ can help you choose which might best benefit your organisation.

If you’d like to know more about the benefits of Lean Six Sigma certification, make sure to see our selection of Lean Six Sigma courses.

How does Six Sigma work?

Six Sigma uses one of two 5-step processes – either the DMAIC or DMADV method, to provide management teams with a structured approach to problem-solving. The name Six Sigma is derived from a statistical analysis term and does not refer to the number of steps in the process.

Below, we’ve detailed each of the two improvement methodologies used by Six Sigma, their purpose, and how they are implemented.

DMAIC

DMAIC stands for Define, Measure, Analyze, Improve, and Control. This method helps solve supply chain performance issues when adjustments to an existing process are needed. It does not help organisations devise solutions to new problems.

The 5 steps of the DMAIC method are:

Define

Define the problem, the output to be improved, the customers, and the processes associated with the problem.

Measure

Collect data from the existing process to establish a baseline for the improvements.

Analyse

Analyse the data to find the root cause of problems, inefficiencies, and defects.

Improve

Develop, test, and implement solutions to improve the process.

Control

Implement the solution and monitor progress.

DMADV

DMADV stands Define, Measure, Analyze, Design, and Verify. While the first few steps of DMAIC and DMADV are the same, the DMADV process helps design new tools to solve new problems rather than helping to fix existing issues on long-running projects.

The 5 steps of DMADV are:

Define

Define the process and the desired outcomes

Measure

Measure and identify critical characteristics of the product or service

Analyse

Analyse the data to find the best design

Design

Design and test the product

Verify

Verify that the design output meets the design input requirements.

DMAIC vs DMADV

While both DMAIC and DMADV use statistical analysis to reduce variations, ensure sustainable, uniform output, and solve problems, they’re made for use in very different contexts. We’ve listed the most notable differences below:

DMAIC DMADV
  • Looks at existing processes
  • Helps design new processes
  • Reduces waste and defects
  • Helps prevent waste and defects
  • Recommends specific solutions
  • Helps discover and create new solutions
  • Sustains improvements through control
  • Measures and validates new designs

Six Sigma certification

Six Sigma is not just a management methodology or organisational culture. It is also a training and certification scheme.

Six Sigma processes are executed by Six Sigma-trained practitioners and staff. There are 4 levels of Six Sigma certification. Each teaches qualification holders to address different aspects of the Six Sigma development cycle.

Six Sigma Qualification Belt Duties
  • Master Black Belt
  • Enterprise-wide statistical analysis
  • High-level planning
  • Mentoring black belts
  • Black Belt
  • Overseeing Six Sigma processes at the project-level or programme-level
  • Mentoring green and yellow belts
  • Green Belt
  • Implementing Six Sigma methods at the project-level
  • Yellow Belt
  • Low-level oversight

Lean vs. Agile vs. Six Sigma

Lean helps reduce waste by cutting out those processes that don’t contribute to the quality of a product. At the end of the day however, there will always be some tasks that, although they may not improve quality or help deliver value, must be completed regardless. This might include time spent organizing documentation or maintaining equipment.

Six Sigma focuses its efforts on making these necessary but non-value-adding processes as simple and quick as possible while also helping refine and improve those tasks that add value and are important to the overall health and quality of a product or service.

In some ways, Six Sigma and Agile are competing methodologies. Six Sigma focuses on standardization by eliminating variation. Agile focuses on flexibility and incremental delivery. Six Sigma demands rigorous documentation and analysis. Agile takes a looser approach, substituting documentation for customer interaction.

Lean and Agile are commonly used together, as are Lean and Six Sigma. While an organisation could, in theory, use a Lean Agile Six Sigma approach, doing so entails a lot of risk due to the complexity of integrating all 3 approaches.

Only mature, experienced, and coordinated teams should consider combing Six Sigma and complex Agile methods such as Scrum. Often there is no real need as Agile practices are inherent to the Lean and Six Sigma mindset. But, using a combination of Lean Agile or Lean Six Sigma is quite a common and well-tested approach to problem-solving in modern organisations, particularly in software development and manufacturing industries.

We’ll look at Lean Agile in another article but while we’re on the topic of Six Sigma, let’s see how Lean and Six Sigma can work together to improve a product:

Lean Six Sigma

Both Lean and Six Sigma are rooted in Lean Manufacturing principles, which is why it is easy to confuse the two and why you’ll often find both often referred to as just Lean Six Sigma.

When combined, these methodologies help practitioners see both sides of a problem – each has a slightly different (but often equally applicable) approach to ‘waste,’ and both share common goals.

The most notable difference is that while Lean is a mindset, Six Sigma is an applicable method.

Lean waste vs. Six Sigma waste

In Lean, waste is defined as any process or task that does not deliver value to the customer. The number of waste types varies depending upon the context but can be generally summarized as:

1. Overproduction
  • Making too much of one thing, as is common in ‘push’ systems of task-management and inventory. It is always beneficial to make only as many products as is required by consumers.
2. Inventory
  • This is waste associated with unprocessed inventory and is closely tied with types 4,6 and 7.
3. Defects
  • Defects are products that do not meet the requirements of the customer. Defects can be created by any number of errors. For example, products that take too long to make may be obsolete by the time they are ready to be delivered.
4. Motion
  • This refers to literal movement. For example, any time a document is delivered by hand instead of being delivered digitally. This is most evident in manufacturing contexts and projects that make extensive use of unskilled labour.
5. Over-processing
  • Lean demands that organisations invest the least amount of time needed to create a product or deliver a service. Anything more than the bare essentials (assuming that the required level of quality has been met) is deemed wasteful.
6. Waiting
  • Any time unused inventory is left in stock, or alternatively, anytime staff are left waiting for the required stock to be delivered (or preceding tasks to be completed).
7. Transportation
  • Similar to Motion-waste. Transportation waste refers to inefficient logistics and supply chains (moving stock using fleets of trucks, for example).

Six Sigma too uses these definitions of waste but adds one of its own in the form of:

Unused employee talent
  • Employees are a great source of new ideas. Failing to use their talents optimally through lack of training is an often-overlooked source of waste and can contribute directly to other sources of waste.

The Lean mindset vs. Six Sigma practice

As stated earlier, one fundamental difference between Lean and Six Sigma is that Lean is a mindset – a set of principles that helps enable smarter decision-making. Lean practitioners follow principles that inform the greater organisational culture to create a space that promotes learning, growth, and experimentation.

On the other hand, Six Sigma is a method – a structured approach to solving organisational problems by following rules and processes.

Supporting Six Sigma is its certification system. Lean is generally implemented holistically by change managers. Six Sigma is implemented by trained Six Sigma professionals at every level in the organisation, each with distinct roles and responsibilities.

Lean is well-suited for autonomous organisational structures that allow collaboration across departments and management levels. Everyone can offer an opinion to help solve organisational problems, regardless of whether they are low-level developers or executives.

Six Sigma relies on hierarchical leadership that is best suited to highly structured organisations. Six Sigma begins with localized problem-solving, whereby issues are escalated depending on scope and complexity.

Six Sigma benefits

Six Sigma is a valuable tool used by organisations across the globe to identify problems, remove the causes of failure, and improve business processes.

Six Sigma can be implemented in any industry if organisations are willing to listen to and investigate customer demands.

Implementing Six Sigma offers a multitude of benefits. However, the five main advantages that Six Sigma offers are:

Reduction of waste

  • The main objective of Six Sigma, reducing wasteful processes, brings a host of secondary and tertiary benefits to your organisation, some of which are listed below.

Improved time management

  • Six Sigma has proven to help employees better manage their time, resulting in increased productivity.

Customer satisfaction

  • Six Sigma encourages organisations to incorporate customer feedback, eliminating defects and helping ensure that products always meet the specified requirements.

Employee motivation

  • Six Sigma engages staff at all levels in an organisation. Even those only trained to the lowest level of certification (Yellow Belt) are made responsible for overseeing development and creating innovative ways to improve output.

Maximizing revenue

  • Simply put, the less waste you generate and the more valuable your products and services are, the more money your business will generate.
IT Learning Library™ online training

Six Sigma and Lean management for process improvement

Six Sigma is a powerful quality improvement methodology originally developed at Motorola in the 1980s. Organisations use Six Sigma and Lean management to reduce defects per million, enhance efficiency, and decrease costs. Lean methodology and Lean principles are integrated with Six Sigma to drive process improvement. Lean projects often apply Lean quality and Lean Six Sigma strategies for operational excellence.

Lean techniques, certification, and quality management

Lean techniques and Lean tools work with Six Sigma certification programmes to ensure quality management standards. Sigma certification, sigma concepts, and sigma improvement focus on reducing variability and meeting customer requirements. Sigma methodologies, sigma principles, and sigma programmes offer systematic approaches for sigma quality management and sigma quality tools.

Lean Six Sigma and sigma training for measurable outcomes

Lean Six Sigma and sigma six initiatives rely on sigma techniques, sigma tools, and sigma training to ensure organisations achieve measurable results. Six Sigma analysis uses statistical methods such as DMAIC and DMADV to identify and eliminate root causes of defects. The Six Sigma approach includes structured Six Sigma belts, such as Six Sigma Black Belt and Six Sigma Green Belt, each requiring comprehensive Six Sigma certification and training.

Six Sigma concepts, methodologies, and expert guidance

Six Sigma concepts and methodologies are widely taught by Six Sigma consultants and Six Sigma experts. The Six Sigma framework is used for Six Sigma implementation, Six Sigma improvement, and Six Sigma management. Six Sigma methodologies and Six Sigma methodology emphasise the use of Six Sigma metrics, Six Sigma performance, and Six Sigma practices for process control.

Six Sigma principles and project excellence

Six Sigma principles and the Six Sigma process are at the core of Six Sigma processes and Six Sigma programmes. Each Six Sigma project is designed to deliver Six Sigma quality using Six Sigma roles, Six Sigma statistics, and Six Sigma strategies. Six Sigma techniques and Six Sigma tools support Six Sigma training and development.

Six Sigma

Six Sigma is a comprehensive methodology that aims to improve business processes by reducing defects and increasing efficiency. Six Sigma methodologies, such as DMAIC and DMADV, provide structured frameworks for process improvement. Training in Six Sigma can lead to various certifications, including the White Belt Certification and Yellow Belt Certification, which introduce the fundamental concepts of Six Sigma. Six Sigma Black Belt holders and those with a Certified Six Sigma Black Belt are equipped with advanced project management skills to lead quality improvement projects. The Six Sigma methodology is aligned with PMI standards and often complements other certifications like PMP. Lean Six Sigma combines Six Sigma methodologies with Lean manufacturing principles to further enhance productivity. The certification exam for Six Sigma requires a deep understanding of its methodologies and practical application in diverse industries. CSSBB is another recognised credential that attests to a professional’s expertise in Six Sigma methodologies. Overall, Six Sigma remains a critical component in the toolkit of professionals aiming to excel in process improvement and quality management.

Introduction to Six Sigma and its purpose

Six Sigma is a disciplined, data-driven approach to improve quality and reduce defects across business processes by applying statistical tools and structured methodologies.

Core methodology and framework

The core Six Sigma methodology commonly referenced is DMAIC—define, measure, analyse, improve and control—which guides improvement projects from problem identification to sustained gains.

Define: setting project scope and goals

Define begins with a clear project charter, stakeholder alignment and measurable objectives that relate directly to customer requirements and business goals.

Project charters help teams focus on measurable outcomes and customer requirements.

Measure: collecting reliable process data

Accurate data collection underpins Six Sigma projects and supports statistical analysis, process mapping and baseline measurement of defects per million opportunities.

Reliable measurement systems reduce errors and improve confidence in results.

Analyse: root cause analysis and hypothesis testing

Teams apply root cause analysis, fishbone diagrams and hypothesis testing to find sources of variation and validate which issues drive poor quality.

Hypothesis testing confirms which factors significantly affect outcomes.

Improve: implementing solutions and pilots

Improvement uses controlled experiments, poka yoke and process redesign to remove defects and improve flow while ensuring compatibility with existing systems.

Pilots validate changes before wide deployment to limit disruption.

Control: sustaining gains with process control

Control plans, control charts and standard operating procedures ensure that improvements persist and that teams can monitor performance over time.

Ongoing monitoring prevents regression and keeps improvements stable.

Tools and techniques used in Six Sigma

Six Sigma tools range from simple mapping and Pareto analysis to advanced statistical process control and regression modelling for deep analytical insight.

Process mapping and value stream analysis

Process mapping helps teams visualise steps, identify waste and prioritise which areas to target for rapid impact on quality management.

Value stream maps highlight non-value steps and handoff delays.

Statistical tools and hypothesis testing

Statistical tools such as control charts, capability studies and hypothesis testing are vital for quantifying variation and validating improvements.

Capability analysis shows whether processes meet customer specifications consistently.

FMEA and risk mitigation

Failure modes and effects analysis (FMEA) identifies potential failure points and ranks them to focus preventive actions where they matter most.

Prioritised risks receive targeted countermeasures reducing failure likelihood.

Design of experiments and advanced analytics

Design of experiments (DOE) and regression help practitioners optimise factors and interactions, especially in complex manufacturing or service environments.

DOE accelerates discovery of optimal settings with fewer experiments.

Implementing Six Sigma projects in practice

Implementation of Six Sigma projects should align with strategic objectives and be supported by sponsors, champions and a trained team structure such as yellow, green and black belts.

Selecting projects that align with business goals

Successful projects target measurable improvements in customer satisfaction, cycle time, cost reduction or compliance and are chosen for value and feasibility.

Project selection tools help compare ROI and feasibility across candidates.

Roles and responsibilities: belts and champions

Belts provide project leadership and analytical skills; a master black belt mentors multiple projects while champions remove organisational barriers and secure resources.

Clear role definitions prevent overlap and ensure accountability.

Combining Lean and Six Sigma for speed

Many organisations combine Lean methods with Six Sigma to address both waste reduction and variation control, often termed Lean Six Sigma.

Combining approaches speeds results while maintaining quality rigor.

How to measure project success

Success is measured by pre-agreed metrics such as reduced defects, improved sigma level, cost savings and sustained process capability improvements.

Tracking benefit realisation proves programme value to sponsors and stakeholders.

Training, certification and career pathways

Certifications—yellow belt, green belt, black belt and master black belt—structure learning and demonstrate capability to lead and support improvement efforts across sectors.

What training options are available?

Training is available through universities, professional institutes and online platforms such as Coursera, offering flexible pathways to certification.

Online programmes often include project mentorship and exam preparation.

How to prepare for a certification exam

Preparation combines studying core tools, completing a project and demonstrating mastery of DMAIC, statistical tools and project management fundamentals.

Mock exams and practical projects improve pass rates and practical competence.

Career benefits of Six Sigma certification

Certified practitioners often gain improved role clarity, higher responsibility for process improvement projects and enhanced career prospects in quality management.

Certification can lead to leadership roles such as process improvement manager or centre of excellence lead.

Applying Six Sigma across industries and functions

Six Sigma is widely applied in manufacturing, healthcare, finance, construction and services to reduce defects, streamline operations and increase reliability.

Manufacturing case studies and impact

Manufacturing organisations report significant defect reduction and improved throughput by applying control charts, SPC and targeted improvement projects.

Yield improvements translate directly into reduced scrap and better margins.

Healthcare and service improvements

In healthcare, Six Sigma reduces errors, improves patient outcomes and shortens wait times by standardising care and measuring outcomes rigorously.

Standard protocols reduce variability in patient treatment and safety events.

Construction and complex project environments

Construction benefits from Six Sigma through better process mapping, supply chain coordination and defect prevention across subcontractors and trades.

Early planning and supplier alignment reduce rework and delays.

Leadership and governance for sustained improvement

Leadership commitment, governance structures and integration with performance management systems ensure that Six Sigma initiatives are prioritised and resourced.

Creating a centre of excellence and governance model

A centre of excellence provides coaching, training and best practice sharing, while governance prioritises projects and measures return on investment.

Coaching from master black belts builds internal capability and consistency.

Aligning Six Sigma with organisational vision

Embedding Six Sigma into strategy helps to align improvement efforts with long-term objectives such as operational excellence and customer-centricity.

Strategy alignment ensures projects support financial and customer goals.

How do you sustain culture change?

Sustaining culture change requires visible leadership, recognition of successes, ongoing training and metrics that reinforce desired behaviour.

Recognition programmes reward teams for measurable improvements and adoption.

Data, measurement and ensuring statistical rigour

Accurate measurement and robust statistical analysis separate successful projects from those that rely on intuition or anecdote.

Data collection best practices

Define what to measure, ensure measurement systems are reliable and collect sufficient data to detect meaningful changes in process performance.

Measurement systems analysis ensures data accuracy and repeatability.

Using control charts and capability analysis

Control charts track process stability, while capability analysis quantifies whether a process meets specification limits and customer expectations.

Regular chart reviews help detect shifts before defects escalate.

Common statistical pitfalls to avoid

Beware of small samples, uncontrolled experiments and misunderstanding variation versus assignable causes when interpreting results.

Educating teams on common pitfalls improves analysis quality and decision-making.

Questions commonly asked about Six Sigma

This section addresses frequent queries from practitioners, managers and individuals considering training or projects.

Is Six Sigma right for my organisation?

Six Sigma is suitable when processes are measurable, defects are costly and leadership is committed to long-term capability building.

Small, targeted pilots can show rapid value before wider roll-out.

How long does certification take?

Certification timelines vary by level: yellow belt can be weeks, green belt a few months with a project, and black belt longer depending on project complexity.

Project completion often determines certification timing more than classroom hours.

What resources does a team need?

Successful teams need data tools, access to process owners, committed sponsors and training in DMAIC and statistical tools.

Access to data and subject matter experts speeds root cause identification.

Can small businesses benefit from Six Sigma?

Yes—tailored, scaled projects that focus on key processes and quick wins can deliver meaningful benefits even for smaller organisations.

Scaled approaches reduce overhead while delivering measurable improvement.

Integrating Six Sigma with other improvement approaches

Six Sigma complements methodologies such as Agile, Kaizen and Lean by bringing statistical rigour and structured problem solving to broader improvement efforts.

Lean and Six Sigma: complementary strengths

Lean focuses on waste reduction and flow; Six Sigma focuses on reducing variation—together they create a powerful approach to process excellence.

Lean tools accelerate delivery while Six Sigma reduces defects through analysis.

Agile integration for product and service teams

For teams delivering products or services, integrating Agile planning with Six Sigma analytics can accelerate learning while maintaining quality control.

Short iterations combined with data-driven checks improve both speed and quality.

Practical steps to start a Six Sigma initiative

Starting requires a clear business case, sponsor commitment, prioritised projects and initial training to develop practitioner capability.

Step 1: Build a clear business case

Quantify expected benefits, estimate costs and identify stakeholders who will sponsor and champion the programme.

Financially justified projects secure faster executive support and resources.

Step 2: Select the first projects

Choose projects with measurable impact, realistic scope and clear owners to demonstrate quick wins and build momentum.

Early wins create credibility for broader deployment and investment.

Step 3: Develop capability and governance

Invest in training, create a governance structure and establish a centre of excellence to support project teams and standardise practice.

Governance ensures consistent methodology and aligns projects to strategy.

Common challenges and how to overcome them

Typical challenges include lack of leadership support, insufficient data quality, resistance to change and poor selection of projects.

Overcoming resistance and sustaining momentum

Address concerns through communication, involve teams in choosing projects and celebrate early successes to demonstrate value.

Engaging teams in problem solving builds ownership and willingness to change.

Improving data quality and measurement

Invest in measurement systems analysis, standardise data capture and train teams in good measurement practice to reduce errors.

Improved data quality increases confidence in decisions and project outcomes.

Balancing quick wins with strategic projects

Mix short-term, high-impact projects with longer strategic initiatives to maintain interest while achieving meaningful transformation.

Portfolio management balances effort across quick returns and deeper transformation.

Case studies and proven benefits

Organisations using Six Sigma report reduced defects, improved customer satisfaction and measurable cost savings when projects are well chosen and executed.

Manufacturing example: Yield improvement

One manufacturer used DMAIC and DOE to increase yield, reduce scrap and improve on-time delivery through focused statistical work.

Improvements in yield often produce immediate cost savings and capacity gains.

Service example: reducing cycle time

In a service context, mapping and process redesign cut processing time, reduced errors and improved customer satisfaction scores.

Faster cycle times often lead to better customer retention and lower operational costs.

Conclusion and next steps

Six Sigma offers a structured, measurable path to quality improvement and operational excellence when implemented with leadership support and solid data practice.

For organisations seeking to adopt Six Sigma, start with a clear business case, build capability through certification and align projects to strategic priorities for sustained impact.

Next steps include selecting initial projects, investing in training for belts and establishing governance to ensure improvements are measurable and maintained over time.