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What is a fishbone diagram or Ishikawa diagram?

Posted by Chris Adams

Article Rating // 13100 Views // 3 Additional Answers & Comments

Categories: Business Analysis, Systems Analysis, Analytical and Problem Solving Skills


A fishbone diagram is a problem-analysis tool that derives it’s name from it’s shape which resembles the skeleton of a fish. Developed by Dr. Kaoru Ishikawa, a Japanese quality control statistician, the fishbone diagram is a systematic way of looking at an effect and identifying and capturing the causes that contribute and result in that particular effect. For this reason, it is sometimes referred to as a cause and effect diagram.

Fishbone Diagram - Ishikawa

The fishbone diagram is useful in:

  1. Identifying the possible root causes of a particular problem
  2. Identifying the most likely cause of a particular problem
  3. Identifying areas that may be good candidates for data collection/measurement and controls

To develop a fishbone diagram:

  1. Draw a horizontal line for the spine of the fish and list the main issue/effect at the head of the fish
  2. Draw 4-6 vertical lines extending above and below the spine of the fish. Each should start at the spine of the fish and slant away from the head of the fish. These “major bones” are used to define the categories of causes that are to be identified. These categories can be whatever you think would work best, but are typically standardized from company to company or team to team. The categories are used to provide a framework for the brainstorming and documenting of causes. Some of the common categories are listed here. The point is you can use whatever categories you team feels is best.
    • Methods, Machines, Materials, Manpower, Mother Nature, Measurements (the 6 M’s, often used for the manufacturing industry)
    • Place, Procedure, People, Policies (the 4 P’s, often used for the service industry)
    • Surroundings, Suppliers, Systems, Skills (the 4 S’s)
  3. Brainstorm on the causes that result in the effect that you are analyzing. For each cause identified, determine which category it falls within and draw a “minor bone” or a line from the “major bone” of the category. Document the cause on the “minor bone”.
  4. For each cause, ask yourself why the cause occurs. Typically a cause is itself and effect of another cause. By drilling down farther and farther you can eventually arrive at the root causes of the effect you are analyzing.
  5. Identify which causes appear under multiple categories. These are often you most likely cause of a recurring issue and deserve the most attention.

Here's a fishbone diagram example:

fishbone diagram example

Chris Adams
LinkedIn Profile



Srinivas Chakravarthi posted on Thursday, March 12, 2009 12:21 AM
Good explanation in detail..

6 Ms are used mainly in Manufacturing, 4/8 Ps are used in Administration and Service industries, 4 Ss are used in Service industry
Srinivas Chakravarthi
Ben posted on Friday, October 2, 2009 5:18 AM
Athough this method is great in performing problem analysis, it can get a bit messy, so the rule to apply when performing this task is "KISS" - Keep it short & simple. Break the problems in to smaller fishbones.
MITESH DODIA posted on Monday, June 4, 2018 5:56 AM
Great explanation !
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