How Many Whys Should I Ask?

“Does it always have to be 5 Whys?” is one of the most frequent questions raised in my training classes. The answer is no. As with most lean tools, it’s important to understand the real purpose of this exercise. In this case, the “5 Why” label is meant to encourage you to ask why more than once or twice, in order to dig below the surface where the symptoms lie, and find the true root cause. The actual number of times you ask why is not critical: I have several examples where 2 why’s works best, and others where you might keep going until you’ve asked the question nine times. 

To practice this method you must go to the gemba to determine the actual cause and effect relationship of what is happening, engaging and involving those affected by the issue in the process. Conducting your investigation from behind a desk or in a conference room will often lead to fighting over symptoms not root causes. This approach will invariably be driven by theories and opinions rather than facts, facts, facts. Avoid the temptation to rely on preconceived notions since they often take less time to investigate. Whenever I hear that time is an issue, I reflect on a quote by the late John Wooden: “If you don’t have the time to do it right the first time, when will you have time to do it over?”

If you don’t have the time to do it right the first time, when will you have time to do it over?

John Wooden

The important issue with this process is not to go too far. Continuing to ask why after you have located the root cause will change the context of the problem, or the scope of control you may have in forming appropriate countermeasures. You want to make sure that your countermeasure effectively addresses the root cause, and all the symptoms up the chain. You want to reach the level at which making a change will effectively and permanently address the symptom that prompted this exercise. (By the way, clearly seeing the chain of events helps you focus on seeing how the root cause of the problem is tied to one of three categories—lack of Standard, lack of following Standard, or wrong Standard—as opposed to being the “fault” of individual people.)

Consider the following example:

Problem: I was late for work.

• Why? I was unable to get there on time.
• Why? I overslept.
• Why? My alarm clock didn’t go off.
• Why? The clocking wasn’t operating as it normally does, in this case flashing when I woke up.
• Why? There was an interruption in the power overnight. (Root Cause)
• Why? There were lightning storms in the area.
• Why? Hot and cold clouds in the atmosphere collided.
• Why? Barometric changes took place.
• Why? The jet stream causes changes to weather patterns.
• Why? There are cycles to the seasons on Earth.
• Why? The Earth rotates.

So. Determining that the earth rotates takes our series of whys way too far. This is what happens if you keep asking why. You change the context of the problem. If I try to form a countermeasure based on this exercise, the logical one being to change the rotation of the earth, how will that address my problem of being late? I’ve set my sights on something that is not within my control.

By recognizing that the overnight interruption in power is the root cause of this problem, I can form an effective countermeasure. I can deal with the power interruption by having battery backups. So while I can’t control the outcome of uninterrupted electricity, I can still address and resolve the problem. Going further than this would be a useless foray into issues that are beyond your scope of control.

Finally, as a good way of checking on your 5 Why experience, it’s good practice to ask WHY downward, and THEREFORE upward, as way of establishing Cause and Effect in your chain.