Fishbone Diagram

Fishbone Diagram can be used to identify, sort and illustrate possible reasons for a problem or condition.

The Fishbone Diagram is a constructive approach to the present situation as the process begins with an in-depth analysis of the problems at hand.

Fishbone Diagram resembles the skeleton of a fish. The existing problem is typed in the ‘spine’ of the diagram and the main reasons behind the problem are written in each ‘bone’. Smaller bones, which are attached to the larger bones, provide more detailed information about the stated reasons. The method helps to structure the problem by providing a good visual overview. It can be used with or without posted notes.

The Fishbone Diagram answers questions such as,

  • What are the possible reasons for……….?
  • What are the underlying reasons behind………?
  • Why do we have a problem with………?

The method is easy to use when the problem area is well defined, and provides a different overview of the problem.

For easy use follow these steps,

  1. Clearly define a problem:
do not define the problem too generally – the ‘head’ should specifically indicate what the problem is.
  2. Draw the Fishbone Diagram:
 First draw an arrow. This is the spine of the diagram. Write the problem in a box at the tip of the arrow. Draw five fish bones attached to the spine. The five bones usually represent the five factors of people, machines, methods, materials and environment.
  3. Find as many reasons for the problem as possible: brainstorming is a good start. Sorting the identified reasons among the five factors gives a clear indication of the dominating factors. You can also check for relevant reasons, if any. Remember that an identified reason can appear in more than one place in the diagram.
  4. Continue:
 Assess if there are additional reasons. Ask ‘why’, look carefully at the diagram and ask,
  • Are there any improvement opportunities?
  • Has the problem already been solved?
  • Is the available information sufficient?

In order to identify which reasons are more important than others, the reasons in the group should be ranked in order of importance. This can; for example, be done by giving each group member points in a scale of 1 to 5 in which 5 indicates the most important and 1 as the least important. The most important reason is assigned 5 points. When all group members have assigned their points, each reason’s total number of points is counted, and the reason with the highest total score is declared the most important.

However, the results cannot be interpreted as proof of the underlying reasons that the group is looking for. So far you have only developed more hypotheses.  Additional data must be collected in order to determine whether the hypotheses are true or false.

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