Six Sigma: Quality Control Tools Used in Six Sigma

A company can use Six Sigma as a quality management tool to improve proficiency in its strategy implementation.

Six Sigma aims, at producing not more than 3.4 defects per million of parts produced in a manufacturing process. It uses a variety of statistics to determine the best practices for any given process.

Statisticians and Six Sigma consultants study the existing processes and determine the methods that produce the best overall results Six Sigma statistically ensures that 99.9997% of all products produced in a process are of acceptable quality; it allows only 3.4 defects per million opportunities.

If a given process fails to meet this criterion it is re-analyzed, altered and tested to find out if there are any improvements. If no improvement is found, the process is re­analyzed, altered and tested again. This cycle is repeated until an Improvement becomes visible.

Once an improvement is found, it is documented and the knowledge is spread across other units in the company so they can implement this new process and reduce their defects per million opportunities.

Six Sigma experts are known as Green Belts and Black Belts. They evaluate the business process and determine ways to improve the existing process. They can also design a brand new business process using DFSS (Design for Six Sigma) principles.

Typically it is easier to define a new process with DFSS principles than refining an existing process to reduce the defects.

Use of Six Sigma

Six Sigma methodology improves any existing business process by constantly reviewing and re-tuning the process. To achieve this, Six Sigma uses a methodology known as DMAIC (Define opportunities, Measure performance, Analyze opportunity, Improve performance, Control performance).

Even though Six Sigma was initially implemented at Motorola to improve the manufacturing process, all types of businesses can profit from implementing Six Sigma.

Six Sigma methodology is used in many Business Process Management (BPM) initiatives these days. These BPM initiatives are not necessarily related to manufacturing Many of the BPMs that use Six Sigma in today’s world include call centers, customer support, supply chain management, and project management.

Businesses in various industry segments such as services industry (example: Call Centers, Insurance, Financial/investment Services), e-commerce industry (example: B2B/B2C websites), and education can definitely use Six Sigma principles to achieve higher quality.

Many big businesses such as General Electric, Sony, Ford Motors, Nokia, Texas Instruments, Hitachi, Toshiba, Canon, DuPont, American Express, Polaroid and Motorola have successfully implemented Six Sigma but the adaptation by smaller businesses has been very slow.

Six Sigma improves profitability through improving quality and efficiency. Evidence shows that many, companies that implemented Six Sigma have seen profit margins grow 20% year after year for each sigma shift (up to 4.8 to 5 sigma).

In fact, Six Sigma allows top leaders in organizations to be proactive, rather than reactive, to quality issues. Proactiveness emerges from the fact that Six Sigma focuses on the process that creates or eliminates the defects rather than on the defects themselves.

Quality Control Tools Used in Six Sigma

Tools that are used in Six Sigma quality control are;

Quality Control Tools Used in Six Sigma

  • Quality Function Deployment (QFD).
  • Cause & Effect Matrix.
  • Failure Mode and Effect Analysis (FMEA).
  • T-Test.
  • Control Charts.
  • Design of Experiment (DOE).

Quality Function Deployment (QFD)

QFD helps Six Sigma Black Belts drive customer-focused development across the design process. QFD is a system. It consists of a set of procedures to identify, communicate, and prioritize customer requirements.

With QFD, Six Sigma teams can more effectively focus on the activities that mean the most to the customer, beat the competition, and align with the mission of the organization.

Cause & Effect Matrix

The C&E Matrix helps Six Sigma project leaders facilitate team decision-making.

The C&E Matrix is a fool that helps Six Sigma teams select, prioritize, and analyze the data they collect over the course of a project to identify problems in that process. Six Sigma teams typically use the C&E Matrix in the Measure phase of the DMAIC methodology.

Failure Mode and Effect Analysis (FMEA)

FMEA helps Six Sigma teams to identify and address weaknesses in a product or process before they occur. Before implementing new products, processes or services.

Six Sigma teams use FMEA to identify ways. An effective FMEA identifies corrective actions required to prevent failures from reaching the customer and will improve performance, quality, and reliability.


The t-test helps Six Sigma teams validate test results using small sample sizes. The t-test is used to determine the statistical difference between two groups, not just a difference due to random chance.

Six Sigma teams might use it to determine if a plan for a comparative analysis of patient blood pressures, before and after they receive a drug, is likely to provide reliable results.

Control Charts

Six Sigma teams use Control Charts to assess process stability. Control Charts are a simple but highly effective tool for monitoring and improving process performance over time because they help Six Sigma teams to observe and analyze venation.

The three basic components of any control chart are a center-line, upper and lower statistically determined control limits, and performance data plotted over time.

Design of Experiment (DOE)

DOE helps Six Sigma Black Belts make the most of valuable resources.

DOE is a statistical technique that encompasses the planning, design, data collection, analysis and interpretation strategy used by Six Sigma professionals! Six Sigma teams use DOE to determine the relationship between factors (X) affecting a process and the output of that process (Y).

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