Improve
The Improve phase develops, tests, and implements solutions that address the verified root causes. Green Belts use structured experimentation, Lean flow concepts, and error-proofing to reduce variation and waste.
Design of Experiments
Design of Experiments (DOE) changes several factors deliberately to learn their individual and combined effects efficiently. A full factorial tests every combination of factor levels, while a fractional factorial runs a chosen subset to save runs when many factors are screened.
Lean flow and takt
Takt time equals available production time divided by customer demand and sets the pace the process must sustain. Balancing work to takt and reducing batch sizes smooths flow and shortens lead time.
Error-proofing (poka-yoke)
Poka-yoke devices prevent mistakes or make them immediately obvious, such as a fitting that only assembles one way. Building prevention into the process is more reliable than relying on inspection to catch defects afterward.