Fishbone Diagram

Fishbone Diagram is a visualization tool for categorizing the potential causes of a problem in order to identify its root causes. In this diagram, the fish head represents the main problem and the fish bones are the potential causes of the problem that are usually derived from brainstorming sessions or research.


  • Duration
    Medium (about 30-60 minutes)
  • Complexity
  • Group size
    3 to 10 persons

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Description Long

The Fishbone, Ishikawa, or Cause & Effect Diagram was first introduced in 1960's by Kaoru Ishikawa of the University of Tokyo. In this method a diagram is used to identify all of the contributing fundamental causes, which have the higher probability of causing a problem. The Fishbone method is beneficial in brainstorming sessions in order to detect all the possible causes for a problem and reveal key relationships among several variables. After the brainstorming process, the facilitator assists the group to rate the potential causes according to their level of significance and diagram a hierarchy. Fishbone diagrams are typically drawn from right to left, with each large "bone" of the fish branching out to include smaller bones containing more detail. Causes in a typical Fishbone Diagram are normally grouped into categories, the main ones of which are: The 6 Ms (usually used in manufacturing industry): Men/People, Machines, Methods, Materials, Measures, Mother Nature 4 Ps (service industry): Policies, Procedures, People, Plant




    1. Sketch the diagram. Identify the outcome or effect to be analyzed.
    2. Use a chart pack positioned visible for everyone, draw a horizontal arrow pointing to the right (spine) and create the effect box (brief description of the outcome).
    3. Identify the main causes contributing to the effect being studied and connect them with the spine using a diagonal line to form a branch.
    4. For each major factor, identify other specific factors, which may be the causes of the effect (sub-causes).
    5. Evaluate the selected causes for rightness, identify increasingly more detailed levels of causes and continue classifying them under similar categories. You can do this by asking a series of why questions.
    6. Analyze the diagram and develop the causes until you have extended an appropriate level of details in order to examine a change and measure its effects.

    Hints from experience

    Make sure that there the group agrees upon the "need" and the characteristics of the "cause statement". A useful way to use this technique with a team is to write all of the possible causes of the problem down on sticky notes. You can then group similar ones together on the diagram. Circle any information that seems to be a key cause, so you can concentrate on it subsequently.

    Tools list

    • Sticky notes
    • Flipchart or Whiteboard


    Hill, R. Cause and Effect Analysis: Identifying the Likely Causes of Problems. Retrieved 5 August 2015, from

    Ishikawa, K., & Loftus, J. (1990). Introduction to quality control. Tokyo, Japan: 3A Corporation.

    Sutevski, D. (2012). Cause and Effect Analysis to Solve Business Problems. Retrieved from

    WBI Evaluation Group. (2007). Fishbone Diagrams. Retrieved 7 August 2015 from,

    Wong, K. C. (2011). Using an Ishikawa diagram as a tool to assist memory and retrieval of relevant medical cases from the medical literature. Journal of medical case reports, 5(1), 120. Retrieved 5 August 2015 from,

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