CI Tools

Here is another example of 5 Why, this time in a restaurant.

Here is another example of how to use the 5 Whys, this time in a service environment.  For example, in a restaurant, the symptom is a customer complaining about the waiting time.  Unfortunately, the way many people would fix this is by apologizing to the customer and make sure that he or she gets the food as fast as possible.  What is the problem?  What is the root cause of the problem?

Remember our friends from Yummy Broth?  They are a small restaurant specialized in soups, but they also served salads and sandwiches.  One day, not one or two, but four customers were complaining about the service.  The truth is that the food was not arriving in a reasonable amount of time, and the front-end supervisor was concerned.  They managed to get food in front of the customers to fix the immediate problem.  The manager does not want this to happen again.  She knows how to use 5 Whys, so next day during their stand-up meeting, she went ahead to analyze the root cause of the situation.

For this problem, probably most people will choose to expedite the food for the complaining customers, a second group would try to find a root-cause and will stop with the third or the fourth why.  Only if you keep digging, will find that the root cause is that there is no standard work.  Even if team members want to help, they could not do the right thing because there is no instruction to do the work.  Without a standard, effective cross-training is not possible.  At least the manager knows better and keeps asking why until the real reason was uncovered.  Now, she should be creating that standard work with the team to organize cross-training.

CI Tools

What is 5 Why analysis? How to use 5 Why and Fishbone diagram for root cause analysis.

One of my favorite tools for root cause analysis is 5 Why.  I like it because it is simple, and you can use it anywhere, and for any situation.  You don’t need to do complicated analysis, take notes or draw anything, you only need to keep your brain asking why until you find the root cause for the problem.  It is also very helpful to see the relationship between different causes. 

This tool is simple but requires practice.  The number of times you ask why depends on each particular situation; five it is not a number written on stone.  If you stop asking why too soon, you will end up far away from the real root cause and asking too many times result in complaints or non-sense answers.

Most of the time the root cause of a problem falls into one of these categories

  1. No standard or inadequate standard
  2. Not following the standard
  3. Inadequate system or equipment

These are the steps to do a Five Why analysis.

  1. Define the problem.
  2. Start describing the problem using all details from the problem definition.
  3. Ask why the problem happens, this is the answer to your first why.
  4. If the answer does not identify the root cause, ask why again.  This is the answer to this why.
  5. Keep repeating the fourth step until you identify the root cause.

My last post was about fishbone, another tool that I used very often.  I like to use it to explore all possible causes because it helps to force people to think beyond the obvious reasons.  Once you complete the cause and effect diagram, you should end up with one or two causes.  At this point, you can use the 5 Whys to drill down the root causes.  

The fishbone I used is from an analysis completed in a food manufacturing plant.  We were looking for the cause of getting excess oil in the body of cans containing oil products.  The fishbone analysis results in two possible causes, both of them related to the equipment used to wash the cans.  The causes were the alignment of the detergent nozzles and the quantity of soap dispensed.  We used the 5 Whys to determine the root cause of each, and we find that the reason was that there was no standard for the setting of the equipment.

Most of the time, when a problem happens, the first thing you see is a symptom.  In this example, the symptom was oily cans.  Without root cause analysis, most probably we would stop at insufficient training, but with fishbone and 5 Why we were able to drill down to the ugly truth, a standard was never established.

Now you have two simple and effective tools to use to find the root cause of a problem.  Practice PDCA and use these tools for RCA, you will see the difference between traditional and lean problem-solving.