Fishbone Diagram for Root Cause Analysis

Abstract

The major cause of uncertainty in organizations is risk. It is crucial to be able to identify those risks and manage them before it can have an impact on the organization’s objectives. The Fishbone diagram, also known as the Ishikawa diagram or the cause-and-effect diagram. was created by Kaoru Ishikawa in the 1960s. It is a visual tool used to identify the possible causes to a problem or effect with the practice of brainstorming. The shape of the diagram resamples the side view of a fish skeleton, hence the name Fishbone diagram [8]. The Fishbone diagram sorts ideas into useful categories and can be helpful in identifying areas for improvement and possible causes that might not be considered using other tools. This article will examine the use of the Fishbone diagram in Risk Management, an overview of the tool and a step-by-step guide to develop a Fishbone diagram, including models and other tools that can be combined in the process.

Application: Fishbone Diagram

Step 1: Identify the problem

The first step for the team is to define a problem or effect that the team wants to analyze. For a successful Fishbone diagram, it is critical to define the problem correctly. Have the team think consider and identify who is involved, what the problem is, and when and where it occurs. When the problem has been identified it is written in a box on the center right-hand side with a horizontal arrow running to it, e.g., on a large sheet of paper or whiteboard. It is also possible to write the problem statement on the center left hand side, whichever you prefer. Resembling a head and spine of a fish, this layout, will give you space to develop ideas in the next steps .

Step 2:

In the next step the team identifies the factors involved in the problem or effect using brainstorming techniques. An example of these factors is Site, Task, People, Equipment and Control. To achieve the best outcome, try to identify as many of these factors as possible. Then, they are written down as branches off the spine of the diagram and resemble the bones .

Useful models

To help in this step of the diagram, teams often use common models of root causes/factors:

5M used in the Fishbone diagram - mainly for Manufacturing .

• Method (Assembly line)
• Mother Nature (Ambient humidity problems)
• Man (Teaching a single employee to find the defect)
• Machine (Age)
• Materials (Hard materials)

This method is also known as the 6 M method with the addition of Measurement.

8Ps used in the Fishbone diagram - mainly for Product Marketing .

• Product
• Place
• Price
• People
• Promotion
• Physical Evidence
• Process
• Performance

4Ss used in the Fishbone diagram - mainly used in the service industries.

• Suppliers
• Surroundings
• Systems
• Skills

Step 3:

In the third step, the team identifies the possible causes associated to each factor determined in the previous step. Again, the team should use brainstorming techniques to identify these causes, and if the problem or effect is large/complex it may be effective to also break down the causes into sub-causes. Have the team think about “Why does this happen?”. Then, the causes and sub-causes are written down as lines coming off each factor branch. If the cause applies to more than one factor it can be added to several branches .

The 5 Why's

The approach of “Five Whys” can be used as a tool for this part