The 5 Whys

The 5 Whys is another Lean Tool that you can use to help identify the root cause of a problem. This tool is most useful when problems involve human factors or interactions.

To use the 5 whys, follow these steps.

• Write down the specific problem, writing it down helps to formalize the problem and describe it completely. It also helps everyone focus on the same exact problem.
• Ask Why the problem happens and then write down the answer.
• Then ask Why again and write down the answer.
• Continue to ask why, it may take you less than 5 whys to get to the root of the problem.

It's really as simple as just continuing to ask why.

Example

Problem Statement: Customers are unhappy because they are being shipped products that don’t meet their specifications.

1. Why are customers being shipped bad products? – Because manufacturing built the products to a specification that is different from what the customer and the sales person agreed to.

2. Why did manufacturing build the products to a different specification than that of sales? – Because the sales person expedites work on the shop floor by calling the head of manufacturing directly to begin work. An error happened when the specifications were being communicated or written down.

3. Why does the sales person call the head of manufacturing directly to start work instead of following the procedure established in the company? – Because the “start work” form requires the sales director’s approval before work can begin and slows the manufacturing process (or stops it when the director is out of the office).

4. Why does the form contain an approval for the sales director? – Because the sales director needs to be continually updated on sales for discussions with the CEO.

In this case only four Whys were required to find out that a signature authority who is not adding any value to the process is helping to cause defects.