Cause and Effect Diagram | Fishbone Diagram (Kaoru Ishikawa)

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Identifying and arranging the causes of an event or problem. Explanation of the Cause and Effect (Fishbone) Diagram of Kaoru Ishikawa. (1943)


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Kaoru Ishikawa Fishbone DiagramWhat is a Cause and Effect Diagram? Description

The Cause and Effect Diagram (Fishbone Diagram) from Japanese quality control statistician Kaoru Ishikawa is a graphical technique that can be used in teams to identify and arrange the causes of an event or problem or outcome. It graphically illustrates the hierarchical relationship between the causes according to their level of importance or detail and a given outcome. Also called: Ishikawa Diagram.
 

Origin of the Fishbone Diagram. History

The Fishbone Diagram was invented by Professor Kaoru Ishikawa of Tokyo University, a highly regarded Japanese expert in quality management. He first used it in 1943 to help explain to a group of engineers at Kawasaki Steel Works how a complex set of factors could be related to help understand a problem.

 

Usage of the Cause and Effect Diagram | Fishbone Diagram. Applications

  • Concentrating on a complex problem in a team effort. Compare: 8D Problem Solving
  • Identify all causes and the the root causes for a specific effect, problem, or condition.
  • Analyze and relate some of the interactions among the factors affecting a particular process or effect.
  • Enable corrective action.

Steps in creating an Ishikawa Diagram. Process

  1. Explain the purpose of the meeting. Then identify, and clearly state, and agree on the problem or effect to be analyzed.

  2. Position a whiteboard or flipchart so that everyone can see it. Draw a box containing the problem or effect on the right side of the diagram with a horizontal spine.

  3. Conduct a Brainstorming session. As a first draft, for the main branches you can use the following Categories:
    • Services industry: the 8 Ps: People, Product/Service, Price, Promotion, Policies, Processes, Procedures, Place/Plant/Technology.
    • Manufacturing: the 6 Ms: Manpower, Methods, Measurements, Machinery, Materials, Mother Nature (environment).
    • Use the above categories by asking for example: What are the People issues affecting/causing the problem?

  4. Identify the main causes contributing to the effect being studied. This could be done applying a Pareto Analysis (80/20 rule) or a Root Cause Analysis.

  5. These main causes become the labels for the sub branches of your diagram.

  6. For each major sub branch, identify other specific factors which may be the causes of the effect. Ask: Why is this cause happening?
  7. Identify increasingly more detailed levels of causes and continue organizing them under related causes or categories.
  8. Analyze the diagram.
  9. Act on the diagram. Remove the causes of the problem. Generic systematic approaches for this are the Deming Cycle or RACI.

Strengths the Cause and Effect Diagram. Benefits

  • Helps to find and consider all possible causes of the problem, rather than just the ones that are most obvious.
  • Helps to determine the root causes of a problem or quality characteristic in a structured way.
  • Encourages group participation and utilizes group knowledge of the process.
  • Helps to focus on the causes of the issue without resorting to complaints and irrelevant discussion.
  • Uses an orderly, easy-to-read format to diagram cause-and-effect relationships.
  • Increases knowledge of the process by helping everyone to learn more about the factors at work and how they relate.
  • Identifies areas for further study where there is a lack of sufficient information.

Limitations of the Ishikawa Diagram. Disadvantages

  • Not particularly useful for extremely complex problems, where many causes and many problems are interrelated.

Assumptions of the Fishbone Diagram. Conditions

  • A problem is composed of a limited number of causes, which are in turn also composed of sub causes.
  • Distinguishing these causes and sub causes is a useful first step to deal with the problem.

Book: Kaoru Ishikawa - Guide to Quality Control -

 

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Recent User Comments
Marek Ćwiklicki - Poland Names of Main Causes "I checked the internet to find out who and when used the original 4Ms as names for the main cause categories (branches). Unfortunatelly I could not find it, even in papers referring to Ishikawa's book from 1982.
Maybe you know when and where this 4M first appeared?"		    0
Jeswan Singh - Malaysia Ishikawa Process in Quality Control and Quality Management "Problem Analysis for quality control/management issues using the Ishikawa process has a high degree of applicability. Its a simple yet effective and is able to generate a fairly accurate solution. Highly recommended for quality improvement programmes at work."    2
Leo van Kampen - Netherlands Determining the Relevance of a Problem "I use the fishbone to determine the relevance of a problem. On the upper side of the fishbone I put the positive characteristics (what are the benefits if the problem is solved). On the lower side the negative (what are the cost elements). I rate all characteristic on a scale from 1-5. Also sub branches are rated. Then I divide the positive by the negative. If the fraction is larger then 1 the problem is relevant if it smaller then one the subject is not that relevant. Relevance is translated to prioritizing. If there are no negative elements then the denominator is infinite small and the fraction becomes infinite large. Mostly quick wins. If there are no positive characteristics the numerator becomes infinite small and the fractal will be close to zero. No relevance."    3
Derek - New Zealand Inventor of Cause and Effect Diagram "If my memory serves me right, the Cause & Effect diagram was an invention of a Scottish teacher. Like so many of the so called Japanese ideas for Quality Improvement they have always been known as excellent copiers of other people's ideas as being their own. Perhaps some of our older folks may be able to recall the name of the Scottish teacher?"    -3
India - Taruna Complex Effect and Cause Relations "Note that Effects and Causes of organizational problems are often interlinked as when a child does not study and the mother scolds him. But the child thinks: because my mother is scolding me every time I don't study.
So we can both say that the scolding occurs because of the child not studying but also that not studying is the effect of the scolding."		    5



Best User Comments
Guus van H. - Netherlands Solution and Effect Diagram "There exists also an inverted Ishikawa Diagram, with the Solution on the left and a big arrow with branches pointing to the right. The branches show the consequences and effects of the solution. You can use it to show, discuss, analyze what the consequences of a particular solution will be."    10
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Compare with the Cause and Effect Diagram: 8D Problem Solving  |  Root Cause Analysis  |  Theory of Constraints  |  Dialectical Inquiry  |  Mind Mapping  |  Pyramid Principle  |  Delphi Method  |  Analogical Strategic Reasoning  |  Action Learning  |  Brainstorming  |  Six Thinking Hats  |  Kepner-Tregoe Matrix  |  RACI  |  Gantt Chart

 

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  └► Mauricio (Peru) Interesting "I am going to try this in my next fishbone"
  └► Pamela (Guatemala) I like it "The only thing that worries me, is how avoid the subjective rate, I am not sure that I will do it only by numbers, when rating always will be any preference involve...."


  └► Grandchamps (Belgium) Complex Effect and Cause Relations "ISHIKAWA chart is a powerful tool. Although limited in complex situations. This tool, as all tools, is only a support in reasoning. The knowledge of advanced ideas, of situation, of context, experience of the participants remains the main trump to find the best solutions."
  └► Gian (Netherlands) Effect is Just Reinforcing the Cause "I tend to disagree, there is 1 cause and (sometimes) many effects. I agree that sometimes the effect is reinforcing the cause, but it is in the time sequence that you will find the answer. If you can demonstrate that "scolding" reinforces the cause, you might simply have found a wrong solution to your problem..."
  └► Koch (Netherlands) Ishikawa Chart Shows (Reinforcing) Interactions "I agree with Gian. The Ishikawa chart can provide insight in how the effects may be reinforcing the potential cause. By analyzing the completed cause and effect chart, interactions and interlinkages become clear. The Ishikawa chart is a diagnozing tool which provides a start for correction, prevention and potential improvement."
  └► Deepak (UAE) Cause & Effect Determined by Observer "Who decides on the cause & effect, it can be an individual or group, it's like a doctor and a patient who at certain point reach a conclusion what was the cause that made the patient ill. So for simple reasons the observer(ownselves or a group of experts or people in general) is the one who indentifies the problems and then looks for the solution. I often use a fish bone diagram and it's me who identify both the cause and the effect."
  └► H. Möller (Deutschland) Causes & Effects Influenced by Type of the Problem "Besides the observer, also the type / nature of the problem influences the (relation between) causes and effects.
For example take the question: Why did Object A hit Object B? This seems a simple problem with straightforward causes and effects. Indeed if A and B are both balls it actually is. And creating a Fishbone chart would be easy.
But if Object A is a hijacked airplane and Object B is the World Trade Center, then there can be a lot of debate on what caused what. The causes and effects are quite debatable and unpredictable. And as Deepak says, it would be impossible to create an Ishikawa Chart to which both the hijackers and the victims would agree."
  └► Joseph (USA) Multiple Causes "I would be suspicious of a C/E diagram that only showed one cause. For instance, I finished one C/E map in which an operator under-charged a raw material which caused a reaction not to go to completion, AND the quality control department misinterpreted the reaction completion analysis results, AND ... There were four independent causes, either of which would have prevented the final negative impact. The sinking of the titanic is another example."
  └► Jim K (Australia) C & E Multiple Causes & User Determined Outcomes "Multiple Causes are a given. Ford's 8D template actually requires a listing of the causes and estimated % contribution.
Be careful not to develop paralysis by analysis by applying 5 [or 55] 'whys' to each of the potential contributors to the effect.
Thus - a good facilitator can keep things on track, but as said earlier - the challenge is to ensure the C&E isn't a collaboration tool that 'dumbs down' the cause based on an inappropriate team formed to conduct the investigation - or a dominate yet inexperienced member."
  └► Pradeep Deo (India) Distinguish Technical and Psychological Effect and Cause Relations "Psychological cause and effect relations can not be compared with technological cause and effect relations. Former involves emotions while later is purly scientific solution."
  └► Ravi Vazirani (India) Interconnection of Various Causes "The C/E relationships of identifying the problem become irrelevant when the cause of the problem has interconnection of various causes and is the effect of the same."