WHAT IS FISHBONE DIAGRAM?
Fishbone Diagram, also known as Ishikawa Diagram or Cause & Effect Diagram, is a diagrammatic
illustration of ‘a problem(effect) & its possible causes’. It is one of the quality tools used to identify &
address a problem in the business areas.
WHY IS IT CALLED ‘FISHBONE DIAGRAM?
It is called a ‘Fishbone Diagram’ because it is drawn in such a way that it looks like a fish skeleton, a Fish
Head with the Spine & Bones. The problem is identified & written in a statement in a rectangular box on
the right side of the board, which forms the Fish Head. A horizontal line is drawn into the box which
forms the Spine. The various causes identified to the problem statement are written as branches
emerging out of the Spine.
The causes are categorized into general classes, which depend upon the industry type. For example the general classes in a manufacturing industry could be:
Man, Machine, Method /Process, Measurement, Material (Raw Material), Environment.
Similarly, for marketing industry the general classes could be:
Product, Price, Promotion, Packing, Place, People.
And for service industry the general classes could be:
Supplier, Surrounding, Skill, System, Standards.
These general classes form the main branches of the spine. Causes further identified in these classes form the sub branches. This exercise is followed till the root cause of the problem is identified. The general principle of ‘5 Why ‘ (asking ‘why’ 5 times to a cause & in turn its causes) could be an effective method to establish a root cause of a problem.
WHEN IS FISHBONE DIAGRAM USED
When a problem is persistent & the causes seem to be various, a Fishbone Diagram is an useful technique to reach the root cause of the problem. It is generally discussed among a group of cross-functional team in a brain storming session with a moderator who draws the actual Diagram as suggestions for possible causes crop up from various resources.
A Fishbone Diagram displays all the possible causes of the problem statement in one place & hence it becomes easy for the management to decide on the action to be taken to address the problem.