pareto-principle

How to complete the Cause and Effect Matrix

This article is the third in a four part series to show you “How to Complete a Six Sigma Root Cause Analysis.” The series covers four tools:

A Cause and Effect Matrix is a tool to help the Six Sigma Project Team prioritize the X’s or Process Inputs. The Cause and Effect Matrix relates process steps to process inputs (X’s) and correlates the inputs to process outputs. In a C&E Matrix, Customer Requirements (or Y’s) are ranked by order of importance to the Customer. The Inputs (X’s) and Outputs are rated by their Interaction Impact. The Cause and Effect Matrix should determine what Key Process Input Variables (KPIV’s) should get the most attention.

Step 1: Enter the Customer Outputs (Y’s)

These outputs come from the “O” (Output) in SIPOC. There should be no less than three outputs under the “O” in the SIPOC(R); therefore there will be no less than three outputs in the Cause and Effect Matrix.

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Step 2: Rate the Importance of the Y’s

Rate the importance of the Y’s (Process Outputs) to the Customer. Use a 1-10 ranking with 1 being the least important and 10 being the most important.

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Step 3: List the Steps of the Process

These are found on the Input Map. Repeat the steps for the amount of process inputs for that step. For example, the step “Setup” in this example has five inputs so we repeat “Setup” in five rows.

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Here is an example of the Input Map where the “Process Steps” and “Process Inputs” are found:

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Step 4: List the Inputs for all of the Steps in the Process

List the X’s (or Inputs) for all of the steps in the process. Do not leave blank rows in between each step. For example, the input “Lighted Area” for the step “Setup” should not have a blank row below it separating the input “Lighted Area” for the step “Setup” from the input “Sandwich Maker” for the step “Apply the Peanut Butter.” Make sure each row and column are filled in.

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Step 5: Determine the Correlation Scores

With the SME’s (Subject Matter Expert’s or Process Owners), determine the Correlation Scores. The Correlation Scores are 0,1,3 and 9. Do not use a 1-10 rating. Using a 1-10 rating allows the project team to “ride the fence” on Inputs that cause debate and the project team will compromise with the score of “5.” This will defeat the purpose of the C&E Matrix.

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Step 6: Prioritizing the Inputs

Sort the “Total” in descending order (from greatest value to smallest value). This will prioritize the inputs based on their effect to the output.

Step 7: Pick the top Inputs

Pick the top three to five as Key Process Input Variables to move into the Failure Modes and Effects Analysis (FMEA).

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Once the C&E Matrix is completed, the X’s or Inputs are prioritized, and the KPIV’s have been identified, then you can move to the next step. The next step in the Six Sigma Root Cause Analysis is the FMEA; this is where we will determine how the Key Inputs can fail.

Conclusion

The Cause and effect matrix is a Lean Six Sigma tool used to prioritize the key process input variables (KPIVs) based on priorities of customer outputs (KPOVs). In other words, it establish the correlation between process input variables to the customer’s outputs during root cause analysis.

How could the C&E Matrix help you in your project?