The Ishikawa Diagram (often called a Fishbone or Cause and Effect Diagram) is one of my favorite tools for finding the root cause (or causes) of problems. It is named after Kaoru Ishikawa, an organizational theorist and professor at the University of Tokyo. The diagram looks like a fishbone and is often called a fishbone diagram. It is also called a Cause and Effect Diagram. At the “head” of the fishbone is the problem to be solved. Traditionally, there are six bones attached to the spine. I have added two more (the last two below). To have all of the headings begin with the letter M (and thus have 6Ms or 8Ms), “People” are sometimes called “Manpower,” and “Environment” is called “Mother Nature.” However, manpower is not reflective of gender in the workplace, and mother nature is just confusing.

• Machines
• Method
• Material
• Measurement
• People
• Environment
• Money
• Management

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An Example of an Ishikawa or Fishbone Diagram

The Ishikawa Diagram below is an example. I’ve indicated many possible contributing factors and linked related issues by drawing lines. I like the way different cause areas are separated for individual analysis and how individual causes can be shown to be linked together.

Creating a Fishbone Diagram, like any brainstorming activity, is an idea-expanding activity. You are adding ideas to the board that could impact the issue at hand. Many of the items entered in the Cause-and-Effect Diagram will not be contributing or root causes. That’s good. It is part of the brainstorming process, and those ideas often lead to other ideas.

Analysis of the Ishikawa Diagram and the next, focusing, activity

Idea-expanding must be followed by focusing activities. The next step here is to group and rank the issues based on the impact on the problem you are trying to solve. Often, there will be one cause that drives the linked issues. This may be a Root Cause. Ideas that don’t seem to be important don’t need to be included.

Questions may arise when compiling this list. This is helpful!

• Throughput instead of quality (High impact)
  • Management focus – A root cause
  • Staffing
  • Stress
  • Working too fast
• Training (High impact)
  • Not trained – More investigation needed? Why were people not trained? It could be money (see below) or management focus (see above)
  • Money for training
• Method (High impact)
  • Using different methods – Is this because the procedure isn’t finalized or due to training?
  • Procedure not finalized
• Work area too hot (Medium impact)

Ranking ideas based on impact and answering the questions that arise helps identify the fundamental Root Causes. Once the Root Causes have been identified, plan activities to fix them.

Teams often stop once solutions are in place and a report has been written. These teams assume that the fix works. If planned, it is usually easy (or at least straightforward) to verify whether or not the solutions implemented have fixed the problem. Decide what data needs to be taken to prove the improvement and ensure a system is in place to collect that data. If data is being taken, it is relatively easy to summarize it and write a final report describing quantitatively how much improvement has been made (or look at the problem again for more possible solutions).

Note that the Ishikawa Diagram might have identified critical issues unrelated to the problem you intended to solve. Don’t lose these issues; instead, solve them in parallel or pass them along to the appropriate people to solve.

Years ago, I struggled with what media to use when creating a Fishbone Diagram with a team. Creating one in a PowerPoint slide deck is possible but cumbersome. I’ve found some useable PowerPoint templates, though. See Smartsheet for an example. Canva and Luchidchart allow for more flexibility when adding and moving items. I use one of these when making a Fishbone Chart by myself. My preference with a group, though, is to use a big piece of paper or a whiteboard. I think this makes the activity a lot more interactive.

Where the Ishikawa Diagram fits in a Quality Management System

A Quality Management System is an integrated set of tools, behaviors, and values that lead to excellent results or Quality. The Ishikawa Diagram is one of many quality tools supporting organizational quality. As a brainstorming tool, it is helpful by explicitly reminding us of several areas of causes (the bones of the fishbone) that could be considered. The “standard” bones were developed for a manufacturing environment. Whether or not your environment is manufacturing, you may find it helpful to change the standard bones for your teams over time.

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