5 Whys is used during the Analyze phase of DMAIC to lead the team to the root cause of the problem. It is an iterative questioning technique which is often used in cases where human interactions are involved and is generally completed without the need of any statistical analysis.
5 Whys analysis starts with a detailed description of the problem at hand, and then consistently asking questions behind the reasons of each iterative answer. Here’s an example which cites the use of 5 Whys to understand the root cause behind the customer dissatisfaction with the shipped products.
First and foremost is, why the customers are being shipped products which is not as per their specification? It is because the manufacturing built the product differently. Why did manufacturing build the product different from that of sales requirement? Due to an error in communication from the sales person to the head of manufacturing.
Now, why was there a communication gap? Because, to expedite the process, the sales person did not wait for the sales director’s approval, as his being out of office might delay or even stop the work. Why does the team needs a sales director’s approval? So that he is updated on the process and can discuss with the CEO.
Here, just 4 questions revealed that a signature, which in this case is non-value added, is the root cause behind the customer’s complaints.
While this technique can be used standalone, or even as a part of the Ishikawa diagram, what is important is to ask the right questions. Only then can an iterative analysis follow and lead the team to the vital cause behind the issue.