The Fishbone diagram is also known as the Ishikawa diagram. It is also called as “Cause and Effect Diagram” that helps the manager to structure a brainstorming session. It immediately sorts ideas into useful categories.
Ishikawa identified five key areas which occur repeatedly in either type of analysis:
These tools make it possible to identify all the roots in a retrospective approach, or, all of the potential effects in a prospective approach.
The fish-bone diagram easily illustrates many possible effects for a process failure in a single diagram. When used as a team approach to problem-solving, this simple process uncovers many less obvious potential causes.
The 5 Whys is a technique used in the Analyze phase of the Six Sigma DMAIC means Define, Measure, Analyze, Improve, and Control.
By repeatedly asking the question “Why”, we can peel away the layers of symptoms which will lead us to the root cause of a problem.
We need to follow the steps mentioned below for the fishbone diagram.
1. We need to agree on the problem statement. It should be mentioned at the mouth of the “fish.” Be as clear and specific as you can about the problem.
2. We need to agree on the major categories of causes of the problem. Major categories often include People, Processes, Machines, Materials, and Environment.
3. We should also brainstorm all the possible causes of the problem. Ask “Why does this happen?” As each idea is given, we should write the causal factor as a branch from the appropriate category. Every cause can be written in several places if they relate to several categories.
4. We should also ask again “Why does this happen?” about each cause. Write sub-causes under the branches’ cause.
5. Until we get to the root cause keep on asking “Why?” tell them to mention all the sub causes under the branch cause.
6. This will help us to identify the cause and then address the root causes to prevent future problems in the project.
It doesn’t matter if you use a graphical representation or build an indented hierarchy Fish-bone, this process improvement tool will greatly help to understand the significant factors involved in a process.
Creating this diagram with a cross-functional team will build not only trust between departments but will cultivate newfound knowledge and understanding for the key influencers in the process.