# Convergent & Divergent Problem Solving

Posted by on Mar 29, 2010 in Problem Solving | 0 comments

Six Sigma is all about reducing variation, understanding which variable or variables wiggle the output the most, and then controlling the variation of those variables to make the output more consistent.  In a Six Sigma project we use tools such as FMEA and cause and effect diagrams to understand those variables.  Brainstorming techniques are used to identify as many variables as possible that affect the process.  In essence, we are using divergent thinking to come up with many potential sources of variation.

But what if we need to find the one dominant cause that is affecting the process?  What if the problem comes and goes?  We could brainstorm causes using our divergent process and if we’re lucky we might stumble on the dominant cause.  A better strategy is to use a convergent approach to solve the problem.

A convergent approach uses process of elimination to determine the dominant cause.  This process can be explained using the game of 20 questions.  Let’s say I’m thinking of a word and you are asked to determine the word I’m thinking of by asking yes or no questions.  One strategy you could use would be to ask whether the word started with the letter a?, b?, c?, etc.  Another strategy would be to ask if the word is an animal?, plant?, mineral?, etc.  A better strategy, using the process of elimination, would be to ask if the word began with the letter a thru k.  It doesn’t matter what the answer is, because half the possibilities are eliminated with the one question.  Continuing to divide the dictionary in half would result in you determining the word in at most 17 questions.

Various convergent tools and techniques can be used to generate clues and help determine the dominant cause using this process of elimination.  I will further discuss the convergent thought process and the various tools and techniques in future postings.  As always, any comments or thoughts concerning this topic are appreciated.