An improvement method based on the scientific approach to problem solving, also known as Plan-Do- Check-Act (PDCA) or Plan-Do-Study-Adjust (PDSA). This method combines the scientific and cultural components necessary to implement and sustain positive change in a specific value stream. 

The PDCA approach corresponds to the three project phases of value stream improvement.

1) Leadership defines the broad need for a project within the organization, the impact of the issue on the organization and the scope of the project. 

2) During a workshop, usually lasting three days, the parties involved in the value stream develop a value stream map, analyze the problems and suggest countermeasures in the form of a future-state map.

3) During the improvement phase, which typically lasts sixty to one hundred and twenty days, the team conducts rapid learning experiments, implements changes to improve the performance of the value stream, and then checks the results. 

In the Lean world, these changes are called "countermeasures" because, unlike "solutions," they do not provide fixed answers but encourage continuous improvement of the process. This methodology also leads to development of a system for managing the performance of the value stream, which enables true continuous improvement.