4 Steps to do Fishbone analysis/Cause and Effect

Fishbone diagram(Ishikawa) or cause and effect diagram

Learn how to do cause and effect analysis and present it in terms of a Fishbone. Fishbone is also known as cause and effect diagram or Ishikawa diagram. Examples presented here will help you to understand the concept and you can also use the same template for your project.

Cause and effect is a systematic approach to explore various causes leading to a problem condition, It is a group activity in which all the stakeholders brainstorm around a problem condition. This problem condition is the “Y” and is also called the “effect”. The final output of the activity resembles a Fishbone – hence it is also commonly called a Fishbone Diagram. The “effect” forms the head of the fish and causes form the bones.

There are four steps to construct a cause and effect diagram

Step1: Brainstorm all possible causes of the problem or effect selected for analysis:
It is a group activity and subject matter experts should be involved, the Black Belt can facilitate the brainstorming. List down all the causes on a board.

Step2: Classify the major causes under the heading 6 M’s or 4 P’s or any thing :
In the previous step we listed all the possible causes which are impacting the “Y” or the problem. But many of these potential causes might be having a very small impact on Y, so we need to prioritize and shortlist the potential causes. We can use multivoting to shortlist the potential causes.
After shortlisting the potential causes we need to categorize them into 6 M’s or 4 P’s, explained later in the article.

Step3: Draw a cause and effect diagram:
Once we have the categorization ready we need to put it on the Fishbone diagram

Step4: Find root cause for each potential X:
Once we have put all the causes in the respective categories, the next step is to do Why? Why? Analysis to reach the root cause for each potential cause. This is a very important step and Why-Why tool is a very simple but effective method of finding root causes.

“ what is 6M in Fishbone?

Example: Fish Bone Analysis-Breakdown conversion


“Why-Why” Analysis helps to structure brainstormed ideas towards problem root causes.
When to Use it When the team needs to explore possible root causes and represent them on a single diagram.

How to Use it

1. State the problem to be analyzed.

2. Ask “Why” – i.e.. what are the first level of causes of the problem?

3. Write each cause on the diagram.

4. For each cause, ask “Why” again and write the answers in the next
column, linked to the previous answer.

5. Keep asking “Why” until no more answers can be suggested.

6. Use the causes listed, especially those on the last level of the diagram,
to generate possible solutions.

7. Review data for evidence of which causes are most important; gather
fresh data if necessary.