Tools for Root Cause Analysis

The success of a process improvement initiative depends on identifying the true root cause for the problem, which can then be targeted for improvement.

The tools featured below aim to spark creative and methodical thinking about the causes of observed problems, problems, helping to assess a wide range of potential causes when trying to find explanations. The following are tips for consideration when using these tools.

• Use those tools as part of the root cause analysis during the last part of the Plan phase of A3 PDCA methodology to suggest ideas about factors contributing to problems and identify the most likely causes that should be investigated further.
• Use Five Whys to uncover the potential cause down to the root level in a quick and focused way.
• Use Fishbone Diagram to arrange and organize many potential causes, focusing on the broad picture.
• Use Eight Wastes to identify waste in the process, focusing on the most common types of wastes.

The tools listed below provide an overview, tips, example, template, and a short explainer video.

Eight Wastes

One of the most critical concepts in lean six sigma is elimination of waste (what is not of value to the customer). Eight Wastes is a waste identification worksheet to help identify the different types of wastes observed in a process.

Instructions:

• Use the acronym DOWNTIME to help identify the most common types of waste in a process:
  • Defects – mistakes, errors, incorrect information and resulting rework.
  • Overproduction – producing more than needed or before it is needed.
  • Waiting – wasted time waiting for the next step in a process.
  • Non-utilized talent – poor use of people’s talent, skills, and knowledge.
  • Transport – unnecessary or inefficient way of moving products and materials.
  • Inventory – excess products and materials not being processed.
  • Motion – unnecessary movement by people, e.g., walking, searching, etc.
  • Extra processing – unnecessary refinements or higher quality work than required by the customer.
• Identify waste by doing a Gemba (process walk), using process flow tools, or engaging employees in continuous improvement activities and encouraging them to voice concerns and suggestions which can help identify waste.
• Use the Waste Identification Worksheet to list all the different types of wastes identified in the process.
• List countermeasures to reduce or eliminate each identified type of waste.

Tips:

• Examine the current state using the Waste Identification Worksheet to help identify a better way and create a vision for continuous improvement going forward.
• Take time to study each of the eight wastes. Below are some tips for identifying and resolving the different types of waste:
  • Defects typically result from mistakes and while it may be tempting to address the issue of defects with more inspection, the best resolution is to uncover the root cause, correct it, and mistake-proof the process.
  • Overproduction often presents a huge waste reduction opportunity. Identifying the waste and understanding the true demand is the starting point and then adapting the process to this demand at all points is the solution.
  • Waiting is often hidden, so mapping and analyzing the process and measuring how long each step takes, including the waiting between steps, can help quantify and address this type of waste.
  • Non-utilized talent can occur in situations when a lot of time is spent on correcting errors and responding to emergencies, not providing employees with opportunities for learning or advancement, not involving employees in process improvement, etc. Wasted human potential is a very damaging type of waste because it can lead to employee turnover, absenteeism, and disengagement.
  • Transportation can be physical movement and electronic movement such as using email to send files back and forth, rather than storing them in a central location. It’s a good practice to keep an eye out for electronic transportation waste in processes.
  • Inventory often goes hand in hand with overproduction. If a product is overproduced, it needs to be stored, tying up space and requiring additional tracking, management, and possibly wasted transportation and motion as well. Additionally, the waste of inventory can be found with unused office supplies, pre-printed forms, or stored promotional materials.
  • Motion is similar to transportation but involves unnecessary human movement in the workspace. Unorganized workspaces where employees spend a lot of time searching for tools and supplies can often lead to the waste of motion.
  • Extra processing is often hidden, and once in place often stays for years. It is subjective and requires understanding the value or purpose of the work, which can only be inferred from internal and external customers by asking them “What is this service or product for? How is it used?” Consider using tools for collecting voice of the customer to understand the value or purpose of the work, and then eliminate what is not needed.

Waste Identification Sheet Template

Waste Identification Sheet Example

Fishbone Diagram

The fishbone diagram, also referred to as cause-and-effect diagram or Ishikawa diagram, is a visual representation of cause and effect, providing a structured approach for brainstorming root causes to a problem and organizing ideas.

Instructions:

• Name the problem you are focusing on. Be as specific as possible.
  • Write the problem (effect) at the head of the fish skeleton.
• Decide which are the major categories of causes and create a basic diagram, mapping the causes as the major bones of the fish (e.g., equipment, people, process, materials, environment, management).
• Brainstorm for more detailed causes (sub causes) under each category and map them as smaller bones of the fish.
  • Work through each category, brainstorming potential causes and asking “why” to get to the sub causes or do an open brainstorming to come up with ideas in any order.
  • Write suggestions on self-stick notes and arrange in the fishbone format, placing each idea under the appropriate category.
• Review and discuss the final diagram. Identify the most critical causes for follow-up investigation.
• Develop a plan for confirming the potential causes are actual causes.

Tips:

• Use this technique for cause identification once you have a clear definition of the problem.
• Use the technique to keep the team focused on the causes of the problem, rather than the symptoms.
• Consider drawing your fish on a flip chart or large dry erase board, so you can modify easily as needed.
• Make sure to leave enough space between the major categories on the diagram so that you can add minor detailed causes later.
• Note that the “five-whys” technique is often used in conjunction with the fishbone diagram – keep asking why until you get to the root cause.
• Use the technique as a cause prevention tool by brainstorming ways to maintain or prevent future problems.

Fishbone Diagram Template

Fishbone Diagram Example

Five Whys

The Five Whys technique is a problem-solving method that involves asking "why" repeatedly to uncover a problem's root cause. This approach prevents a team from being satisfied with superficial solutions which may treat symptoms rather than root causes and won’t fix the problem in the long run. It fosters understanding, prevents recurrence, promotes teamwork, and streamlines improvement efforts.

Instructions:

• Ask why a problem happened or select any cause from a fishbone diagram and ask why it occurred. (Why 1)
• Ask “why does this outcome occur?” (Why 2)
• Select one of the reasons for Why 2 and ask “why does that occur?" (Why 3).
• Continue in this way until you feel you have reached a potential root cause.

Tips:

• There isn’t anything sacred about the number 5. Sometimes you may reach a root cause after two or three whys, sometimes you may have to go more than five layers down. Based on research, you typically discover the root cause going down five layers.
• Stop whenever you have reached a potential cause that the team can act on.

Five Whys Template

Five Whys Example