In process improvement efforts, defects per million opportunities or DPMO (or nonconformities per million opportunities (NPMO)) is a measure of process performance. It is defined as
A defect is defined as a nonconformance of a quality characteristic (e.g., strength, width response time) to its specification. DPMO is stated in opportunities per million units for convenience: Processes that are considered highly-capable (e.g., processes of Six Sigma quality) are those that experience only a handful of defects per million units produced (or services provided).
Note that DPMO differs from reporting defective parts per million (PPM) in that it comprehends the possibility that a unit under inspection may be found to have multiple defects of the same type or may have multiple types of defects. Identifying specific opportunities for defects (and therefore how to count and categorize defects) is an art, but generally organizations consider the following when defining the number of opportunities per unit:
* Knowledge of the process under study
* Industry standards
* When studying multiple types of defects, knowledge of the relative importance of each defect type in determining customer satisfaction
* The time, effort, and cost to count and categorize defects in process output
Six Sigma is a process improvement set of tools and strategies, originally developed by Motorola in 1986. Six Sigma became well known after Jack Welch made it a central focus of his business strategy at General Electric in 1995, and today it is used in different sectors of industry.
Six Sigma seeks to improve the quality of process outputs by identifying and removing the causes of defects (errors) and minimizing variability inmanufacturing and business processes. It uses a set of quality management methods, including statistical methods, and creates a special infrastructure of people within the organization ("Champions","Black Belts", "Green...