This Article is the second in a four part series to show you “How to Complete a Six Sigma Root Cause Analysis”. The series covers four tools:
- The SIPOC(R) Diagram
- The Input (or Variables) Map
- The C&E Matrix
- The FMEA (Failure Modes and Effects Analysis)
The Core equation in Six Sigma is Y=f(X1, X2, X3, Xn). In order to understand our “Y” or Output, we must first define our “X’s” or Inputs. The Input Map (or Variables Map) is a tool used to define those Inputs.
Step #1: Enter the Process Steps. These steps should come the “P” (Process) in your SIPOC.
- There should be no more than 12 steps
- If there are more than 12 steps, you should review your project scope because it may too large
Step #2: List the Process Measurable Outputs.
- These are the Measurable Outputs from the Process Step
- The Outputs are related with the Steps not the Inputs. In other word, I can have 20 inputs in the “Input” column with 3 outputs in the “Output” column
Step #3: Enter the Process Inputs.
- As a general rule, the Input should be no more than a 3 word Noun (not an Adverb or Adjective)
- Go to Gemba, Walk the Process and take notes of all Inputs to the Process. Don’t determine that an Input is Insignificant and not write in on the Input Map, we will use a tool called the C&E Matrix to sift out the Unimportant “Inputs”.
Step #4: List the “Type” of Variable as “U” (Uncontrollable) or “C” (Controllable).
- Controllable (C): Inputs that you can adjust while the process is in action
- Example: While in the process of mowing a lawn, you can adjust the height of the mower or the speed at which you push the mower
- Uncontrollable (U): These are Inputs that you either can’t control or are unwilling to control (because of cost, company politics, etc.)
- While mowing a lawn, you cannot control the weather as it can change from sunny to raining.