Definition

Six Sigma is a data driven, customer focused, and result oriented methodology which uses statistical tools and techniques to systematically eliminate the defects and inefficiencies to improve processes.

Six Sigma methodology has the following characteristics:

  • Customer centric
  • Process focused
  • Data driven/ factual
  • Breakthrough performance gains
  • Structured improvement deployment
  • Validation through key business results

Mathematical Interpretation

Sigma, represented by the Greek alphabet ‘σ’, stands for standard deviation from the ‘mean’. ‘Six Sigma’ represents six standard deviations from the mean, the simple average of data.*.

  • USL – Upper specification limit for a performance standard. Any deviation above this is a defect.
  • LSL – Lower specification limit for a performance standard. Any deviation below this is a defect.
  • Target – Ideally, this will be the middle point between USL and LSL.