Fishbone Diagram: How to Use the Cause-and-Effect Diagram

A fishbone diagram is a visual tool to help identify the possible causes of a problem somewhere in your business process. It gets its name from its resemblance to a fish skeleton, with the main problem at the head, a long line backward, and diagonal prongs categorizing problem causes à la the ribs of a fish.

Kaoru Ishikawa, a Japanese organization and business expert, initially came up with this diagram in the 1960s to assist companies like Kawasaki in fulfilling their product development potential. As a result, you might hear some people refer to the fishbone diagram as the Ishikawa diagram as well.

Knowing your way around the fishbone diagram methodology can work wonders for your organization. Here are three potential pros to using this framework to solve problems:

• Greater detail: As a visual tool, the fishbone diagram gives organizations a lot of leeway to go into as much detail as possible. While you can technically draw out this diagram on any kind of blank surface, it’s useful to do so on a large flipchart or whiteboard. As you start directly writing in problem causes or placing them on sticky notes, you might realize you need more space than you thought at first.
• Improved analytical capacity: By using your fishbone diagram as a mind map, you can work with your team members to initiate a thorough and wide-reaching brainstorming session. Everyone can include what they say as a root cause to the problem at hand. Since everyone can utilize their brainpower to solve problems in this way together, you’ll have greater problem-solving capability overall, too.
• More understanding of issues: With a fishbone diagram in tow, you can accomplish a root cause analysis to better understand what caused an issue and how to fix it. This greater sense of understanding leads to improved workflow, more durable products, and an increased ability to understand how your quality management process works as a whole. Identifying why a problem arose in one specific instance could also help you improve an entire process across the board.

It’s fairly simple to draw up a fishbone diagram and put it to tangible use. Follow these seven steps for a basic fishbone diagram template:

1. 1. Ask what the problem is. To start drawing this cause-and-effect diagram, identify a problem statement. Suppose your company designs cars and quite a few models are coming off the assembly line with a defective taillight. In this case, your problem (represented at the head of the fish) would be something like “Car has a defective taillight.” Draw a long line backward to the left of the problem statement.
2. 2. Categorize the causes of the problem. Sketch out diagonal lines on each side of the line behind the problem statement to represent the categories of potential causes. There are many fishbone diagram examples available online to choose from featuring premade categories, but you can also define your own. Potential categories might include issues with your workforce, raw materials, machinery, and the like.
3. 3. Explain these causes. After you identify causes in the abstract, start to write out contributing factors to these causes. For instance, suppose you haven’t implemented a thorough enough training program for your employees. You would find the appropriate category (perhaps something like “workforce issues”) and briefly write in this specific issue alongside it.
4. 4. Include subbranches if necessary. Main causes and major categories might not be enough to cover issues in as much detail as you would hope—in this case, feel free to draw additional lines on the fishbone diagram representing sub-causes. For example, you might have one main “materials” category as a cause and then two sub-cause categories for “domestic materials” and “imported materials.”
5. 5. Question these causes. Examine all of the cause-and-effect relationships you and your team have listed. Try out the five whys technique—ask “Why?” five times to better home in on why something might be causing a problem. The more you’re able to reason backward from the effect to an increasingly granular cause, the more likely you are to find the exact root cause of the issue in your process.
6. 6. Start to plot out solutions. Once you identify all the possible causes of the problem, do your best to address these concerns, bottlenecks, or other issues to improve your products as soon as possible. Only do so when you feel you’ve managed to come close to the exact cause of the initial issue represented at the head of the fishbone diagram. Trying to address all potential issues rather than the most likely one will prove needlessly costly.
7. 7. Take a step back. At the end of this troubleshooting process, see if you were able to identify and fix the root cause of a problem. Continuous improvement is always possible, so keep using fishbone diagrams as useful tools to suggest new metrics for product enhancement in addition to more specific kinds of problem-solving. Ask when drawing out fishbone diagrams might prove most useful in your project management cycle as a whole.

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