Six Sigma builds on causal thinking to solve problems sustainably. It is important to stop fire-fighting and work to eliminate the root causes of problems.

The equation y=f(x) stands for cause and effect: Whenever there is something you want to change (Y), you should investigate how to influence it (X). Unfortunately, there are very few processes where the output is influenced by one input only. In reality most processes have a number of influencing X variables (y=f(x1,x2,…,xn)). It is our challenge to separate the important Xs from the less relevant ones.

Some practical context:

  • Having a problem typically means something needs to be changed – your Y. Use the Y in your problem definition.
  • Having a clear objective means knowing which Y to change and to which extent.
  • Knowing the root causes of a problem means you know which Xs strongly influence your Y.
  • You have found a solution to a problem when you know how to set the Xs to achieve your target Y.

Learn more about this topic in our Lean Six Sigma Basics Online Course (Demo currently not available for Internet Explorer).