Five why special case: Branching

- Problems often have more than one root cause. In those cases, when using the five Y's, you can use branching to cover the different causes your team is identifying. Take for example, a company that repairs industrial vacuum cleaners. They receive boxes from the customer and enter the return authorization order number and the machine serial number into their production control system. Unfortunately, customers are complaining that the repairs are taking longer than the time quoted. So the logistics manager and warehouse operators get together to analyze the situation and initiate a five Y analysis. The problem is defined as late delivery of repaired equipment to the customer. Why is the delivery late? Because the repair process is stopped midway and the equipment is returned to the warehouse. Why? Because the data entry clerk has entered the wrong information into the system. Why? Because the person unpacking wrote down the incorrect serial numbers for the vacuum cleaner. Why? And here's where the team created two separate branches. For branch one, the unpacking person wrote down the wrong serial number because they couldn't see it very well. Why couldn't they see it? Because the lighting in the warehouse is too low. Why? Because the wrong type of light was installed. Why? Because maintenance didn't check the type of bulb that was required for the warehouse. Why? Because maintenance changed the bulb assuming they installed the right bulb. Why? Because the maintenance manual does not include details about lighting types for each area. For this branch, the countermeasure was to revise the maintenance manual to include details about light bulbs for each area in the plant. For branch two, the unpacking person wrote down the wrong number because they were not adequately trained and didn't check the serial number against the return authorization document. Why was the operator not adequately trained? Because there was no detailed process for unpacking. Why? Because the receiving process had not been clearly mapped out. As a countermeasure, the team created a step by step process for unpacking that called for the operator to write down the serial number and check it against the return authorization document before passing the information on to the data entry clerk. Did you notice branch one had eight Y's and branch two had only five Y's? The number five in the five Y methodology is a guideline to make sure we ask why more than once. Five is not meant to be an absolute number. As you can see, running a five Y analysis can sometimes be a bit messy when you go down a cause and effect chain, only to realize the logic doesn't make sense, especially when branching. So I suggest you use a whiteboard or pencil and paper since you might be erasing and revising until the cause and effect logic makes sense, until you're sure the root cause has been found.