What is Six Sigma?

Six Sigma is a strategy model designed to help businesses embark on a continuous improvement process by limiting errors and defects. The Six Sigma methodology aims to eliminate waste, inconsistency, and discrepancies that challenge the quality of products and services of a business, company, or organization.

For nearly a century, industries have strived to improve efficiency to increase their output while still producing high-quality products. To satisfy this quest, experts have designed models, reviewed, and tested them for their practicality in the business world.

In 1986, Bill Smith developed the Six Sigma methodology, which today, companies and organizations use as a measure of quality near perfection. This article explains the Six Sigma methodology.

Understanding Six Sigma

The Six Sigma methodology comes from the field of statistical quality control. It follows a data-driven and statistical approach at a granular level to detect errors in business processes.

In Statistics, the lower-case Greek letter Sigma (σ) denotes the standard deviation from the mean value. Therefore, the sigma concept would mean that there would be errors to eliminate at any point of deviation. In the 1920s, Walter Shewhart followed this concept and introduced a three sigma from the mean methodology to improve Lean manufacturing processes.

Six Sigma comes from the statistical bell curve, where one Sigma denotes one standard deviation from the centerline of a control chart. An "extremely low" defect is when the process has six Sigma, 3 below, and 3 above the centerline.

Even though Shewhart's methodology was effective and remained a standard for decades, there were still significant errors in the processes that slowed it down or incurred more costs. So, in 1986, Bill Smith proposed a more comprehensive methodology that involved collecting and analyzing data, with six Sigma as the point of correction. Today, a company using the Six Sigma methodology collects data and then uses statistical tools to determine the baseline sigma. Using the baseline sigma, the company can tell their deviation from the Six Sigma and identify defects that need future improvements.

Six Sigma is now a standard methodology after publication by the International Organization for Standardization (ISO) under the publication number ISO 13053:2011. Meaning professionals and organizations can receive Six Sigma certifications after successfully using the publication for Six Sigma training.

What is Lean Six Sigma?

Most companies use Lean manufacturing as a strategy to eliminate waste and improve their bottom line. Lean manufacturing companies incorporated Six Sigma into their lean concept to create the Lean Six Sigma methodology. Lean Six Sigma is a quantity-driven strategy that works best in large-scale production environments and is prone to high quantity waste. It focuses on using the Six Sigma methodology to reduce even more waste while improving efficiency.

Companies using Lean Six Sigma can speed up production, improve quality, cut production costs and remain competitive.

Six Sigma methodologies

The Six Sigma strategy aims to optimize business processes for near-perfect performance by minimizing variability. A two-pronged approach makes this possible:

• Problem Identification - You determine what you have and what you should have. At this point, you identify the errors and determine their impact on the overall outcome.
  
  
• Problem-Solving - You devise a model that fixes the errors and implements them to move from what you have and achieve what you should have.

Two quality management methodologies come into play for Six Sigma to achieve these results. They come in five phases that a business has to follow to get results. They include:

• DMAIC
• DMADV

Let's discuss each of these methodologies.

DMAIC

DMAIC is the most common methodology among Six Sigma adopters. It focuses on improving current processes incrementally and stands for: Define, Measure, Analyze, Improve, and Control.

Organizations can use this data-based method for process improvement projects. It should follow the prescribed order to be effective.

Here's a breakdown of the five-step process:

Define

Before you can deal with a problem, you must first define it. So, in this step:

• Clearly identify the 'what' in the problem
• State the goal of the project
• Outline the scope of the project
• Identify the available resources
• Set a timeline for the project

Simply put, this step allows you to table whatever information you have on the process improvement project and seek clarification. Using that information, you can identify the problem, your customer's needs, what you require to meet those needs, and set other project goals.

Measure

Collect data on the project and use it to determine the scope of the problem. By doing this, you'll better understand the problem and position yourself to solve it. The data collected at this point will act as a reference point to measure your progress at the end of the project.

Analyze

The problems identified in the first step have a root cause that must be eliminated. This step allows you to analyze the multiple root causes using complex data analysis tools, validate them, and select them for elimination.

The most common analysis techniques include:

• brainstorming
• 5 Whys Root Cause Analysis
• Value Stream Mapping
• Voice of the Customer

Improve

Establish creative ways to eliminate the problem from the root cause. Test the simple solutions first and see whether they suffice. A plan-do-check-act (PDCA) cycle ou cycle planifier-faire-vérifier-agir (PDCA, « plan-do-check-act » en anglais) can also help you test the identified solutions and allow you to create a workable implementation plan.

Using a tool for monitoring action plans, which are numerous in these projects, also helps navigate the process. UTrakk’s Project Module is a good example, but here are some other tools and methodologies commonly used at this stage:

• The 5S
• Mistake Proofing
• Kaizen
• Benchmarking

Control

In this step, you need to implement activities to ensure the sustainability of the implemented improvements. These could include Standard Operating Procedures (SOPs), control charts, audits, and also recommendations for future projects.

Control and sustainability are often the weakest links of improvement processes. Active supervision tours are an excellent way to follow up with staff members. Including specific checkpoints in your Gemba Walk checklists help maintain awareness and accountability toward processes and results.