Six Sigma Control Limits and a Few Applications


  • Ambika C. Mount Carmel College, Bangalore
  • Prakash R. Vijaya College, Bangalore
  • Nagaraja Rao C. Vijaya College, Bangalore



Sigma (σ) is a Greek letter that has become the statistical symbol and metric of process variation. Six sigma is a disciplined, customers focused process designed to help organizations to move towards the creation of near perfect products and services. Six sigma (6σ) increases quality by reducing variation, defects and costs. 6σ is used in almost all fields of human activity. 6σ has been considered a powerful business strategy that employs a well structured continuous improvement methodology to reduce process variability and drive out waste within the business processes using effective application of statistical tools and techniques. This article i) gives the general introduction about the concept of six sigma, ii) briefs about the two 6σ methodologies DMAIC and DMADV, which are most commonly used by the organizations to achieve 6σ performance level, iii) discusses some of the applications of these limits in reducing the process variability. Some remarks about the results of applications of 6σ, the future requirements and benefits of 6σ are also discussed.