What is a Fishbone Diagram?

Fishbone diagram or Ishikawa diagram is a modern quality management tool that explains the cause and effect relationship for any quality issue that has arisen or that may arise. It provides the visual representation of all the possible causes for a problem to analyze and find out the root cause. It is a tool that can be used both proactively and reactively.

Now, why is it called a Fishbone diagram? It is not without any reason. The name comes from the shape this tool takes after its formation. Its structure resembles the bone structure of fishes. Problem is written in the rightmost part, which is the fish’s head. In the left runs its spine, which has bone-like arrows pointing to main causes. Under those main causes are determined the sub-causes.

Reference Fishbone or Ishikawa Diagram and its components:

This diagram is drawn on an excel sheet, alternatively, this can be made on a word or paint as well. There are also many online websites and templates that provide you ready-to-use diagrams. As can be seen in the diagram, the problem/issue is mentioned in the right. Then main causes are mentioned on the tip of bones stretching from the spine bone. Under these main causes are mentioned the causes and sub-causes.

How to Create a Fishbone diagram?

Make the head of the fish in the right. Here we mention the subject that needs our attention.
Draw a backbone in the left.
Draw branches to the backbones that will list the main causes. List four to eight main causes.
Under these main causes are listed the causes and sub-causes. These can be identified by organizing a brainstorming session or by minutely following the whole process and identifying all the possible reasons that can lead to quality damage.

Identification of Factors Causing a Defect

For identification of factors we may consider the breaking the all the reasons under the following main-causes:

Machine
Materials
Methods
Personnel (Men)
Measurements
Environment

Alternatively, we may also use the 5 why’s a technique or the 4 P’s (Product, Policies, Procedures, and Plant). We can also create our own main causes in order to group the causes as we deem fit.

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Examples of Fishbone (Ishikawa) Diagram

Example #1

Let’s try an example where the problem that needs our attention is wrong/delayed/damaged delivery. The possible reasons can be many like the wrong packaging was used that led to damage during transit, the wrong product was released for delivery or the addressed labeled on the product wasn’t correct. We can classify the same in main causes and present it in the fishbone diagram like below:

Example #2

Let’s take one more example. Looking at how well we addressed the above problem, we have hired on as consultants by a burger store to identify the reasons that can lead to the preparation of a bad quality-burger. The problem sounds tasty, I mean interesting, doesn’t it?

Advantages

This technique is widely used in product design, quality improvement, and defect minimization.
Instead of pointing out just one reason, this technique gives us a gamut of all the possible reasons that assists not only in identifying the root cause of the current problem but also avoid any future mishappening.

Limitations

This technique should not be used as a one-time activity. This activity should be undertaken continuously to be proactive in determining any possible loophole in the process.

Conclusion

The fishbone diagram is a visual representation of cause and effect relationships. It is simple to use the tool, yet very effective in improving a process and the quality of a product or service. With its continuous implementation, an organization can be proactive in determining any process shortcoming and can address problems quickly and more accurately.

This tool can be very effectively used by the business organization to achieve six-sigma results in their processes. It can be drawn on a paper, a spreadsheet, any word processing software or with the assistance of much online software.

Fishbone Diagram