1. Observe measurements over time

Invented by Shewhart, whose disciple Deming considered himself to be, the theory of variation has been taken up by Six-Sigma, TPS and SPC, but its applications are more general than in industry or the service sector. The theory was designed to be simple. It can therefore be easily applied to all the measures and indicators monitored in an organization, with a minimum of information.

The theory of variations is a key management tool, insofar as it can be used to interpret variations in measurements or indicators over time, and to guide decisions or actions for improvement.