SIX SIGMA – STATISTICAL APPROACH OF QUALITY IMPROVEMENT

Six Sigma is a set of techniques and tools for process improvement. It is a disciplined, data-driven approach and methodology for eliminating defects (driving toward six standard deviations between the mean and the nearest specification limit) in any process – from manufacturing to transactional and from product to service. Six Sigma seeks to improve the quality of the output of a process by identifying and removing the causes of defects and minimizing variability in manufacturing and business processes.

Six Sigma is a management philosophy developed by Motorola that emphasizes setting extremely high objectives, collecting data, and analyzing results to a fine degree as a way to reduce defects in products and services. The Greek letter sigma is used to denote variation from a standard. The philosophy behind Six Sigma is that if you measure how many defects are in a process, you can figure out how to systematically eliminate them and get as close to perfection as possible. In order for a company to achieve Six Sigma, it cannot produce more than 3.4 defects per million opportunities, where an opportunity is defined as a chance for non-conformance.

There are two Six Sigma processes: Six Sigma DMAIC and Six Sigma DMADV, each term derived from the major steps in the process. Six Sigma DMAIC is a process that Defines, Measures, Analyzes, Improves, and Controls existing processes that fall below the Six Sigma specification. Six Sigma DMADV Defines, Measures, Analyzes, Designs, and Verifies new processes or products that are trying to achieve Six Sigma quality

Six Sigma is a relatively new concept as compared to Total Quality Management (TQM). However, when it was conceptualized, it was not intended to be a replacement for TQM. Both Six Sigma and TQM have many similarities and are compatible in varied business environments, including manufacturing and service industries. While TQM has helped many companies in improving the quality of manufactured goods or services rendered,  Six Sigma has the potential of delivering even sharper results.

Total Quality Management is often associated with the development, deployment, and maintenance of organizational systems that are required for various business processes. It is based on a strategic approach that focuses on maintaining existing quality standards as well as making incremental quality improvements. It can also be described as a cultural initiative as the focus is on establishing a culture of collaboration among various functional departments within an organization for improving overall quality.

In comparison, Six Sigma is more than just a process improvement program as it is based on concepts that focus on continuous quality improvements for achieving near perfection by restricting the number of possible defects to less than 3.4 defects per million. It is complementary to Statistical Process Control (SPC), which uses statistical methods for monitoring and controlling business processes. Although both SPC and TQM help in improving quality, they often reach a stage after which no further quality improvements can be made. Six Sigma, on the other hand, is different as it focuses on taking quality improvement processes to the next level.

The basic difference between Six Sigma and TQM is the approach. While TQM views quality as conformance to internal requirements, Six Sigma focuses on improving quality by reducing the number of defects. The end result may be the same in both the concepts (i.e. producing better quality products). Six Sigma helps organizations in reducing operational costs by focusing on defect reduction, cycle time reduction, and cost savings. It is different from conventional cost cutting measures that may reduce value and quality. It focuses on identifying and eliminating costs that provide no value to customers such as costs incurred due to waste.

 TQM initiatives focus on improving individual operations within unrelated business processes whereas Six Sigma program focus on improving all the operations within a single business process. Six Sigma projects require the skills of professionals that are certified as ‘black belts’ whereas TQM initiatives are usually a part-time activity that can be managed by non-dedicated managers.

Six Sigma initiatives are based on a pre-planned project charter that outlines the scale of a project, financial targets, anticipated benefits and milestones. In comparison, organizations that have implemented TQM, work without fully knowing what the financial gains might be. Six Sigma is based on DMAIC (Define-Measure-Analyze-Improve-Control) and DMADV (Define-Measures-Analyze-Design- Verify) that helps in making precise measurements, identifying exact problems, and providing solutions that can be measured.

Six sigma is also different from TQM in that it is fact based and data driven, result oriented, providing quantifiable and measurable bottom-line results, linked to strategy and related to customer requirements. It is applicable to all common business processes such as administration, sales, marketing and R & D.  Although many tools and techniques used in Six Sigma may appear similar to TQM, they are often distinct as in Six Sigma, the focus is on the strategic and systematic application of the tools on targeted projects at the appropriate time. It is predicted that Six Sigma will outlast TQM as it has the potential of achieving more than TQM.

In today’s market scenario, quality is of utmost importance. If you believe it is natural to have defects, and that quality consists of finding defects and fixing them before they get to the customer, you are just waiting to go out of business. To improve speed and quality, you must first measure it–and you must use a common measure. The common business-wide measures that drive our quality improvement are defects per unit of work and cycle time per unit of work. These measures apply equally to design, production, marketing, service, support and administration. Everyone  is  responsible  for  producing  quality;  therefore,  everyone  must  be  measured  and  accountable  for  quality. Measuring  quality  within  an  organization  and  pursuing  an  aggressive  rate  of  improvement  is  the  responsibility  of operational management.  Because  higher  quality  ultimately  reduces  costs,  the  highest  quality  producer  is most  able  to  be  the  lowest  cost  producer  and,  therefore,  the  most  effective competitor in the marketplace. Increasing importance of Six Sigma concept is due to the fact that it attends this aspect of quality improvement with a very structured, disciplined and calibrated methodology.