Fishbone or Ishikawa diagrams were created in 1968 by Kaoru Ishikawa who was a Japanese Professor at the University of Tokyo and was famous for his inventions for quality management.
The fishbone diagram is being used across several software and manufacturing organizations as a simple visualization tool to depict various potential causes to a problem. It provides a structured way to organize and represent data in a meaningful manner.
The fishbone diagram is a pictorial representation and categorization of possible known causes to a problem, usually gathered during brainstorming. Brainstorming is a creative technique where a group of people come together and generate a list of ideas to solve a problem. You will read about the brainstorming technique later in this book.
You can apply the fishbone diagram method in solving day-to-day problems as well. This technique can be used whenever there are many possible causes to a problem or whenever there is a need to identify causes to a complex problem.
This technique is mostly conducted in a group with people from different fields of expertise. However, this method can also be used by an individual as a tool to structure one’s thoughts and identify root causes.
Shape of a Fishbone Diagram:
The below figure (Fig. 1) shows the shape of a typical fishbone diagram:
Fig. 1: Shape of a Fishbone Diagram
As you can see, the shape of the above diagram resembles a fish skeleton! Hence, this diagram is popularly known as the Fishbone Diagram.
To create a fishbone diagram, the problem that one is trying to solve is written on the right-hand side within a box or a circle. Next, a central arrow is drawn that connects to the problem box or circle. This is called the ‘Main Arrow’ (refer to Fig. 2).
Fig. 2: Fishbone – Problem
The major categories for the causes to this problem are written on the branches connecting to the main arrow (refer to Fig. 3).
Fig. 3: Fishbone – Categories
Each of the primary causes to the problem are then notated as a branch from the appropriate category. The secondary or the sub-causes branch-off the primary causes and so on (refer to Fig. 4).
Fig. 4: Fishbone – Primary & Secondary Causes