Six Sigma is a methodology for creating high performance products and services with continuous improvement and keeping a vision of the undergoing process as well as upcoming roles and targets. It is more of a management technique, not a standard or certification.

Origin of Six Sigma

Six Sigma was developed by Motorola in 1980s. It was first used by General Electric for process improvement in 1995.

Why Six Sigma?

As we go through the progress graphs of major organizations, most of the failures to meet customer requirements and defects are related to the lack of efficient management techniques rather than incompetency of the employee. Hence it becomes a responsibility of the management sector to come up with highly efficient management strategies leading to lesser defects and higher productivity.

The major reasons for following the six sigma approach can be concluded as follows:

  • To maintain continuous growth in the organization along with achieving the desired goals and meeting deadlines
  • To meet customer requirements and thus maintain credibility with the customers
  • Lesser defects and rework. Healthy work environment
  • To have a clear business output for setting up further goals through proper analysis

Basic Terminology

CTQ: Critical to Quality

CTQ is a critical characteristic of a product or service. It includes the issues that can directly impact customer satisfaction.E.g. Expected Time of Resolution of an issue, Customer Handling

This characteristic can be determined by successful customer surveys or face to face group interaction etc.

QFD: Quality Function Deployment

It directly links what customer wants with what we deliver. It is important to understand the customer requirements and highlight the critical areas which directly have an impact on customer satisfaction.

FMEA: Failure Mode and Effect Analysis

This deals with analysing the possible failure ways and assigning appropriate corrective measures in such case to avoid business loss. It mainly enhances the reliability of the product or service by maintaining failure handling checks while the development is in progress.

DPU: Defects per Unit

It is the number of defects existing in a single unit.

DPO: Defects per Opportunity

It is the number of defects which exist with respect to the number of opportunities for defect.

For example: An employee details form has 4 errors. The defect per unit will be 4 errors/1 unit forms i.e. 4

Now, in each form there were 10 fields to be completed. So, defects per opportunity will be

4 defect/ (1 unit * 10 opportunity) i.e. 0.4

Defect per Million Opportunities will be DPO value * 1,000,000

E.g. DPMO = 0.4 * 1,000,000 = 400,000

Six Sigma Methodologies

The two major Six Sigma methodologies are as follows:


It is a data driven strategy for improving the existing business process as per the problems faced during the process and analysing the corrective actions required.

Define – Measure – Analyse – Improve - Control

  • Define the issue or project module you want to focus on
  • Measure the severity of the issue faced and the parent process
  • Analyse the process to obtain the major reason for the failure
  • Improve the process by providing the appropriate fixes and corrective actions to prevent further defects
  • Control the further progress of the process using the new methodologies


Define – Measure – Analyse – Design – Verify

  • Define the issue or project module you want to focus on
  • Measure the customer requirements
  • Analyse the capability of the process to meet customer requirements
  • Design the best possible method to implement the process and also meet customer requirements
  • Verify whether the process designed is efficient enough to meet the customer requirements and render the best possible result.