Pretty sure that 0.0001% of you care about the root cause brainstorming sessions during the Analyze phase of #DMAIC in #LeanSixSigma, but ...

Don't just brainstorm on the RCA of the causes with highest variation and worst performance against target, but ALSO on the RCA for the smallest variation and best performance in your stratification. Preferably do those in parallel with different groups, and then compare - are the variations in same things causing both best and worst outcomes?