This Article is the first 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 SIPOC(R) is an Acronym for Supplier Input Process Output Customer Requirement. The SIPOC Diagram is one of the Most Important tools in a Lean and/or Six Sigma project. This tool will help the team identify whether they have focused on the right process. The SIPOC(R) will also help the team to understand who their Customers are and what are their Requirements
The SIPOC(R) helps us break down our process into External Inputs and their Suppliers; Process Steps; and Outputs, Customers and their Requirements. This diagram allows us to see the process from the 30,000 foot view.
The Picture below is a basic diagram to understand the SIPOC(R):
I like to use the example of Mowing a Lawn to describe the Diagram above. The Scope of “The Process” is inside of the box. The “External Inputs” (left of the box) are those things that have to be fed to the process in order for the process to work.
Let’s say that the Scope of The Process of Mowing the Lawn starts with: You are standing behind the lawnmower, it is running and ready to mow the lawn. What has to be fed to The Process in order for the Process to Work?
- Someone (or Something) to push the lawnmower
- A Lawnmower
- Knowledge of how to work the lawnmower
- Proper Weather
Why is it important to understand our Internal Inputs? Our focus during the Lean and Six Sigma Project will be on the “P” in the SIPOC. What if we are focused on the wrong process? By understanding our “External Inputs”, we might find one or more “External Inputs” have a significant effect on our “Process Output”.
By not addressing that Input, we may not make a significant enough improvement to our “Process Output”. One of the Most Powerful aspects of a SIPOC is to help a project team determine if they have the right focus.
Step #1: Fill out the “Process Name”
- Use verbs or adjectives
- In this example: “PBJ Process” is the Process Name.
Step #2: Fill out the High Level steps in the Process – This is the Focus of the Lean and Six Sigma Project
- There should be no more than 12 high level steps
- Use verb or adjectives – how does the process operate?
- In this example: setup, apply the peanut butter, apply the jelly, final assembly
Step #3: Fill out the “Outputs” section.
- Should have no less than three Ouputs (this is important in a later Six Sigma Root Cause Analysis Tool).
- Use nouns – what does this process produce?
- This shouldn’t be written in the Positive (like “Good Taste”) or Negative Sense (like “Bad Taste”) only in the Neutral Sense (like “Taste”)
Step #4: Who are the “Customers”? Who will benefit from this process? Who will be upset if this process doesn’t work as required?
Step #5: What are their (the Customers) requirements? List requirements for each “Output”.
- For Example: The “Output” of “On-Time” has a Requirement of “12:00 +- 10M
Step #6: What are the External Inputs to the “Process”?
- The External Inputs are those Inputs that have to be fed to the process in order for the process to work
- These “External Inputs” are external to the “Process” that our Six Sigma Project is Focused.
Step #7: Who Supplies the Inputs?
- You don’t need to list every specific supplier unless the specific supplier detail is important to the variation in the output.
- For Example, If the variation in taste is impacted by the different suppliers of Peanut Butter, then we would list the suppliers in that level of detail.
- Once the SIPOC(R) is completed, and the Scope (or Focus) of the Process that is to be Investigated has been verified, then you can move to the next step. The next step in the Six Sigma Root Cause Analysis is the Input (or Variables) Map.