Applying the right lean tool for a given problem follows directly from mastery of the lean principles.
Description of Five Whys Tool
The Five Why's is a simple process to follow for solving any problem. It starts with writing or having an effective problem statement. Problem statements determine the next direction to take when solving a problem. If the problem statement is wrong, every step that follows will be wrong.
Proper Uses of Five Why's Tool:
1. As a structured approach to solve problems as they occur
2. As a framework for a team to work through a more complex problem
Improper Uses of Five Why's Tool
1. To emphasize the person or blame, turning the Five Why's into the Five Who’s
2. To emphasize documentation at the expense of applying the tool. When problem solving becomes a tedious, desk-intensive process, it is a punishment that gets used as little as possible.
Problem statements should describe the current condition, use data where possible, and describe the gap in performance. You should also be open to changing the problem statement as you learn more during your investigation. In writing problem statements, you should avoid describing the solution, postulate as to the expected cause, be vague or ambiguous, or combine multiple problems into one.
Some examples of good problem statements include:
• Currently entering data into two different systems; tasks are on average 20 percent late from scheduled time
• Overall customer complaints are up 50 percent
• The #3 press is consuming $2,000 in repairs monthly
Finding the Why Answer
Once the problem statement is determined, you can begin using the Five Why's to determine the root cause. Ask why to the problem statement and then ask why to that again five times. Five is not a magic number; sometimes it might be two, others nine. You should not try to jump why's, but precede one why at a time.
You can test each answer to your "why" by asking, "If I remove this, will the previous answer go away?" If the answer is no, you haven’t answered why correctly and you should explore it further. If you can’t immediately answer a why, go and observe or collect data until you can see the current condition clearly enough to answer. Because of this, you may not complete a Five Why in one conversation, but may have to observe, collect data and other activities at each level of why. You have gotten to the end, or the root cause, when you can describe the cause of the problem in terms of an activity, connection or flow.
Finding the Root Cause
As an example, let's look at a problem concerning a key piece of equipment that has failed:
Why did the equipment fail? Because the circuit board burned out.
Why did the circuit board burn out? Because it overheated.
Why did it overheat? Because it wasn’t getting enough air.
Why was it not getting enough air? Because the filter wasn’t changed.
Why was the filter not changed? Because there was no preventive maintenance schedule to do so.
That is now a root cause that can be solved. By focusing on the question WHY, we are more likely to avoid using the other W question: WHO.
The purpose is to fix the system, not just remove the symptom. If we aren’t clear about the difference between symptoms and problems, we will not find the root cause effectively. Symptoms are the part we see -- the part on the surface. Symptoms are how we know we have a problem. Problems themselves are the cause of that symptom. As an example, if I see oil on my garage floor and I clean up the oil, is the problem fixed? No, you just fixed a symptom of the problem, not the problem. The problem is the engine leaks.
Finding the Countermeasure
Once the root cause is determined, a countermeasure to the problem must be found. Creativity and lean tools are your most powerful allies in this part of the process. Focus on nothing but the root cause in determining the proper countermeasure. All the other work -- from problem statement to the Five Why's -- helps to get you to this point.
A vital final step of the process is verifying that the solution worked. This should be done by first seeing that the countermeasure is sustainable and then making sure that the original condition -- the symptom -- has been eliminated. There are two purposes. The first is to ensure we met our objective: eliminating the adverse condition. The second is where learning occurs. By verifying each countermeasure, we learn what works and what doesn’t, improving our knowledge both of the process we are trying to manage and improve, in addition to the problem solving process itself.
Variations on the Tool
The Five Why's can be built into many other problem-solving processes. Many companies create proprietary problem solving processes that are based on having a common way to communicate or save for learning and history. The Five Why's can be utilized as a formal part of a larger process or by the user to determine the root cause, which then gets input into the formal process. Also, tools, such as Six Sigma, can help find the answer to each successive ‘why’ being asked, but does not replace the process of digging down layer by layer.
How the Five Why's Tool Relates to Rules and Principles
The Five Why's most obviously and directly relates to the principle of Systematic Problem Solving. Without the intent of the principle behind you, the Five Why's will likely be a shell of a process and not used effectively.
Key behaviors that must accompany the Five Why's include:
• surfacing problems quickly
• using them as opportunities to move closer to the ideal state
• focusing on the process, not on blaming the person.
The principle of Create a Learning Organization is also greatly enabled through the practice of the Five Why's. The Five Why's can become the primary driver of daily learning about the management and improvement of the process. By finding the root cause and then verifying the effectiveness of the countermeasure, deep knowledge of the process can become institutionalized.
The Lean Learning Center