Ishikawa fishbone diagram. Causal Diagram: Method Description and Application Features

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Ishikawa fishbone diagram. Causal Diagram: Method Description and Application Features
Ishikawa fishbone diagram. Causal Diagram: Method Description and Application Features

One of the seven powerful project and quality management tools is the fishbone root cause analysis chart. The method came to us from Japan. And it is this tool that is believed to have helped Japanese goods enter the world market and take a stable position on it. But today, the fishbone chart, also named after its discoverer Kaoru Ishikawa, is used for more than just researching product quality or improving sales.

General information

The Ishikawa Fishbone Diagram is one of the graphical methods or methods that are applicable in determining the most significant (root) cause-and-effect relationships in the study of a situation or problem.

This is a problem visualization method: a graphical representation of the relationship of a nonconformity (problem) with the causes that affect itinfluence.

This graphic scheme is named after one of the most famous management theorists - professor from Japan Kaoru Ishikawa. He developed this method and put it into circulation in the middle of the 19th century. Graphically, the diagram looks like the skeleton of a fish, which is why it is called a "fish bone".

fish skeleton
fish skeleton

Steps of work

The Ishikawa diagram in the management of product quality, resources or projects involves several stages of work, namely:

  • At the initial stage, it is necessary to identify and collect all the factors and causes that may affect the expected result.
  • Next, you should group them into blocks in accordance with the meaning, causes and effects.
  • Next, the factors are ranked within each block.
  • Then you can start analyzing the picture. As a result, there is a release from those factors that cannot be influenced.
  • At the last stage of the analysis, factors that are insignificant or unimportant are ignored.
  • ishikawa chart
    ishikawa chart

Graphic rules

When drawing a fishbone diagram, large arrows of the first order are drawn to the main horizontal arrow, which depicts our object of analysis, which indicate the root factors or their groups that affect the object. Arrows of the second order are brought to the arrows of the first order, arrows of the third order are brought to them, and so on until all factors influencing the object or situation are taken into account.

In this case, each next arrow in relation to the arrow of the previous order is a cause, and each subsequent one is a consequence.

The size of the picture and its shape are absolutely not critical. The main thing is to correctly distribute the subordination and mutual dependence of factors.

At the same time, the clearer the fishbone is, the better the diagram looks and reads.

ishikawa quality control chart
ishikawa quality control chart

Rule of five "M"

Despite the apparent simplicity of construction, Ishikawa's "fish bone" requires a thorough knowledge of the object of analysis from the performers, a clear understanding of the mutual dependence and influence of factors on each other.

To facilitate the construction of such a scheme, you can use the rule of five "M", which was proposed by its author. It lies in the fact that when analyzing a set of real situations, the primary (root) causes are the following:

  • Man (people) - causes that are associated with the human factor.
  • Machines (machines or equipment).
  • Materials - reasons related to resources or materials.
  • Methods (methods, technologies) - reasons related to the organization of processes.
  • Measurements (measurement or finance).

This is why the Ishikawa diagram is sometimes called the "5M analysis scheme".

fish skeleton diagram
fish skeleton diagram

Brainstorming tool

So, let's start building a fishbone diagram.

Take a large piece of paper or board. From the rightside in the middle we write the problem and draw a horizontal line from it. We write out the causes that affect the problem, and draw segments connecting them to the main line. Starting work on second-order arrows.

The same reason can appear in different branches of the diagram. Its elimination will lead to the solution of several problems at once.

And the relationship between factors and causes is clearly demonstrated by the hierarchy of arrows.

It is this "fish bone" that is an excellent tool for teamwork, or brainstorming. At the same time, the attention of the participants is focused not on complaints and regrets, but on specific constructive proposals to eliminate the causes that led to the current situation.

Main principles of working with the scheme

When compiling and analyzing the Ishikawa diagram, it is important to adhere to the following rules:

  • It is necessary to take into account all, even the most insignificant factors and problems. Only in this way it becomes possible to find the root cause of the situation, and hence the search for the most effective solution to it.
  • In the course of the analysis, it is important to evaluate the factors by their significance. Thus, the root factors are identified - those that influence the situation the most.
  • When the most complete information is entered into the diagram (names of causes, dates, names of participants, product names), the situation or problem becomes clear and obvious.
  • Important! The process of searching and analyzing, interpreting problems and factors is a fundamental part in creating a holistic picture and those specific actions or directionsmovements that can solve a problem or solve a situation.
  • building an ishikawa diagram
    building an ishikawa diagram

Pros and cons

The obvious advantages of such graphical analysis are:

  • Unleashing personal and collective creativity.
  • Identification of all interrelated causes and factors that lead to a problem or situation.
  • Finding unusual ways to solve a problem.
  • Simplicity and easy applicability.

But this method has its drawbacks:

  • No validation rules. Thus, it is not possible to trace the logical chain in the opposite direction - from the result to the root cause.
  • Composed "fish bone" may be too complex a scheme without a clear structure. This will only complicate the analysis and exclude the possibility of correct conclusions.
  • causal diagram
    causal diagram

The Golden Key of Success

The Ishikawa diagram is applicable not only in the field of management, trade and quality management. This is an understandable and accessible form for structuring all the possible causes of the real situation that has appeared, identifying the most significant of them and determining ways to correct them and get out of the problem area.

This method of graphical analysis has found its followers in education and medicine. And besides, it is applicable in simple everyday situations.

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