Home News What is a Fishbone Diagram and When is It Used?

What is a Fishbone Diagram and When is It Used?


A fishbone diagram is designed to be used primarily to look at the cause and effect concerning solving problems. These can be personal challenges, but their frequent use is within the business and academic circles.

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What is a Fishbone Diagram?

Dr. Kaoru Ishikawa created the first fishbone diagram. While in existence since the 1920s, it was shared widely from 1968.

The diagram was created to examine the cause and effect of business problems. Furthermore, while sometimes referred to as the Ishikawa Diagram, the hope of the inventor was for it to prove helpful to analyze more significant issues.

The appearance is much like a fish laid flat on a table, with the head oriented to the right side. While the diagram may not include the outline of a fish, it will still be obvious it’s a fishbone diagram. This is because it will come with the problem in the head on the far right and a spine attached, running the entire length from right to left.

With every diagram, the fishbone has ribs jutting out on either side of the spine. These are used via labels usually to state the causes of a problem. Sub-branches point away from each rib detailing individual sub-causes or ideas relating to it that are worthy of inclusion.

When Fishbone Diagrams Are Used

There are a few ways to use fishbone diagrams, as outlined below.

A Different Approach to Brainstorming

Brainstorming new ways to fix a flawed process, developing products into a market beater, or better understanding why a business isn’t profitable enough can be helpful.

Listing problems in a spreadsheet or within Word doesn’t encourage creative thinking. It also isn’t easily shareable. The reaction is usually, “Yes, okay…” but with little active feedback and assistance beyond that.

Instead, using a fishbone diagram that visually shows the suggestions to date, recipients can be encouraged to fill out the various ribs and sub-branches with their contributions. With the added reassurance that “No idea is a bad one” to urge things along, businesses can obtain valuable additions that wouldn’t have surfaced otherwise.

Six Sigma and DMAIC

The DMAIC method from the Six Sigma management dogma is frequently used with a fishbone diagram.

The diagram is a quality assurance tool and breaks down into ribs for Define, Measure, Analyze, Improve, and Control. These are further broken down into their respective sub-branches to look at a problem thoroughly and to find better solutions to those that already exist today.

New Product Improving Upon the Old

Companies looking at what’s already available in the market and being determined to improve upon new products have been developed.

By adopting a fishbone diagram as a critical tool, companies can list design defects or faults with existing products and their solutions. Furthermore, unsatisfactory product features can also be shown with new ideas added that improve upon them.

Solve Manufacturing Problems

The 8 Ms in manufacturing is frequently used as a standardized method to isolate problems in the factory.

Sub-causes are discussed and added to the fishbone diagram to suggest possible related causes under each main one. This involves listing Method, Manpower, Mother Nature, and Maintenance on one side of the spine, and Management/Money, Measurement, Material, and Machine on the other. These form the 8 Ms (there is a 6 M version too).

People involved with operational efficiency in manufacturing will usually be familiar with these diagrams. They will know how they’re used and get the best from their implementation.

Root Cause Analysis

Seen often as a cause-and-effect diagram, fishbone diagrams are also used to work through business problems relating to accidental causes and undesirable effects.

A problem may be determined, but the cause is not readily understood. Perhaps some initial suggestions for possible causes are worth exploring in detail. These can be added to the diagram. However, these may get managers thinking and offer suggestions that lead to further review.

Multiple diagrams may be created to complete a detailed analysis of what is happening and why depending on how severe the problem is. Only after doing so can a solution be devised to resolve the business problem.

How to Think About Fishbone Diagrams

If you’re a new manager and you’ve not learned about fishbone diagrams before, they can be a little daunting at first. Nevertheless, persevere because they’re instrumental in a business setting.

View them as a method to list the primary starting points for a particular problem. From there, additions are made beneath these to provide suggestions for causes, effects, or fixes to try.

While fishbone diagrams aren’t perhaps used as frequently as possible, they have their place and time. They’re also incorporated into Six Sigma, which is still used in many businesses.