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Fishbone or Ishikawa diagram

Understanding the Ishikawa Fishbone Diagram: A Simple Guide to Cause and Effect Analysis

In the world of problem-solving and quality management, many tools help organisations identify and address issues effectively. One such tool is the Fishbone Diagram, also known as the Ishikawa Diagram or Cause and Effect Diagram. This blog will provide a simple and comprehensive guide to understanding and using the Fishbone Diagram for better problem-solving.

What is a Fishbone Diagram?

The Fishbone Diagram, named for its resemblance to a fish’s skeleton, is a visual tool used to systematically identify and present the possible causes of a specific problem or effect. It was created by Dr. Kaoru Ishikawa in the 1960s, a Japanese quality control expert. Hence, it is also known as the Ishikawa Fishbone Diagram or Cause and Effect Diagram.

Why Use a Ishikawa Fishbone Diagram?

Using a Ishikawa Fishbone Diagram helps organisations:

  1. Identify Root Causes: It aids in pinpointing the underlying causes of a problem rather than just addressing symptoms.
  2. Structured Analysis: The diagram provides a structured way to analyse problems by breaking them down into smaller, more manageable parts.
  3. Team Collaboration: It promotes teamwork by involving various stakeholders in brainstorming and discussing potential causes.
  4. Visual Representation: The visual nature of the diagram makes it easier to understand complex issues.

Components of a Ishikawa Fishbone Diagram

A Fishbone Diagram consists of several key components:

  • Head: Represents the problem or effect being analysed.
  • Spine: The main line that connects the head to the various branches.
  • Branches: Major categories of potential causes, which are typically divided into six main categories of causes.

Six Categories of Causes in the Fishbone Diagram

The six categories of the Ishikawa Fishbone Diagram are known as the 6Ms:

  1. Manpower: This focuses on human factors like communication, experience, and education.
  2. Machine (Machines, Tools & Computers): This examines equipment and technology’s role in contributing to the problem.
  3. Measurements: This considers quality standards and measures reliability used in the process.
  4. Materials: This evaluates the quality and suitability of materials used.
  5. Mother Nature/Environment: This analyses external influences like weather and noise pollution.
  6. Method: This explores processes, logistics, and administrative tasks associated with the problem.

Example of a Fishbone Diagram

Let’s consider an example to understand the Fishbone Diagram better. Suppose a manufacturing company is experiencing a high rate of defective products. The head of the fishbone would represent the problem: “High Rate of Defective Products.”

Branches and Categories in the Ishikawa Fishbone Diagram:

  1. Methods: This branch examines the processes and procedures used in production.
    • Inadequate training
    • Outdated procedures
    • Lack of standardisation
  2. Machines: This branch looks at the equipment and tools used in production.
    • Equipment malfunctions
    • Lack of maintenance
    • Use of outdated technology
  3. Materials: This branch investigates the raw materials used.
    • Low-quality materials
    • Incorrect material specifications
    • Supplier issues
  4. Measurements: This branch focuses on the measurement systems and data collection methods.
    • Inaccurate measurements
    • Inconsistent data collection
    • Faulty measurement tools
  5. People: This branch looks at the human factors involved.
    • Insufficient training
    • Lack of motivation
    • Poor communication
  6. Environment: This branch examines the physical and environmental conditions.
    • Unfavourable working conditions
    • Temperature fluctuations
    • Poor lighting

How to Create a Ishikawa Fishbone Diagram?

Creating a Fishbone Diagram is a straightforward process. Follow these steps:

Step 1: Define the Problem

Clearly define the problem or effect you want to analyse. Write it down at the head of the diagram.

Step 2: Identify Major Categories

Identify the major categories of potential causes related to the problem. Common categories include Methods, Machines, Materials, Measurements, People, and Environment. However, you can adjust these categories to fit your specific situation.

Step 3: Brainstorm Potential Causes

For each major category, brainstorm potential causes of the problem. Encourage input from various team members to get a comprehensive list.

Step 4: Draw the Diagram

Draw the main spine and branches of the diagram. Write the problem at the head and the major categories at the end of each branch. Add sub-branches for each potential cause identified during brainstorming.

Step 5: Analyse and Investigate

Examine the diagram to identify the most likely root causes of the problem. Prioritise these causes for further investigation and corrective action.

Practical Tips for Using Fishbone Diagrams

Here are some practical tips to make the most out of Fishbone Diagrams:

  1. Involve the Right People: Include team members with different expertise and perspectives to ensure a comprehensive analysis.
  2. Stay Focused: Keep the brainstorming sessions focused on the specific problem at hand. Avoid getting sidetracked by unrelated issues.
  3. Use Real Data: Support your analysis with real data and evidence wherever possible. This helps in validating potential causes.
  4. Prioritise Causes: Once you have identified potential causes, prioritise them based on their impact and likelihood. This helps in focusing efforts on the most critical areas.
  5. Review and Revise: Regularly review and revise the Fishbone Diagram as new information becomes available. This ensures that your analysis remains accurate and up-to-date.

Benefits of Ishikawa Fishbone Diagrams

Fishbone Diagrams offer several benefits that make them valuable tools for problem-solving and quality management:

  1. Comprehensive Analysis: They provide a structured approach to analysing problems, ensuring that all potential causes are considered.
  2. Enhanced Collaboration: By involving team members from different departments, Fishbone Diagrams promote collaboration and collective problem-solving.
  3. Visual Clarity: The visual representation of causes and effects makes it easier to understand complex issues and communicate findings to stakeholders.
  4. Root Cause Identification: Fishbone Diagrams help in identifying the root causes of problems, enabling organisations to implement effective solutions.
  5. Continuous Improvement: By regularly using Fishbone Diagrams, organisations can foster a culture of continuous improvement and proactive problem-solving.


The Fishbone Diagram, also called the Ishikawa Fishbone Diagram or Cause and Effect Diagram, is a great tool for finding and analysing the root causes of problems. Its clear structure and easy-to-understand visuals make it useful in many industries. By involving your team, using real data, and focusing on the main causes, you can solve issues more effectively and keep improving.

Whether it’s manufacturing defects, medical errors, customer complaints, or software bugs, the Fishbone Diagram can help you find the root cause and apply effective solutions. Use this simple yet powerful tool to boost your problem-solving skills.

By understanding and using the Ishikawa Fishbone Diagram, your organisation can better identify, analyse, and solve issues, leading to better results and higher efficiency. So, next time you face a problem, remember to fish for the root cause with a Fishbone Diagram!

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