The Fishbone Diagram has many names like “Problem Analysis Tool”, “Cause effect identification tool” and “Root cause Analysis Tool”.
A tool used to analyze possible causes of a
specific problem or condition
What is a Fishbone diagram?
Dr. Kaoru Ishikawa, a Japanese quality control statistician, invented the Fishbone Diagram. The Fishbone Diagram is an analysis tool that provides a systematic way of looking at effects and the causes that create or contribute to those effects. The design of the diagram looks much like the skeleton of a fish. Therefore, it is often referred to as the fishbone diagram.
Cause effect diagram is used to assist teams in categorizing the many potential causes of problems or issues that may exist in Business or even in day to day life, in an orderly way and in identifying root causes.
As problems come in many shapes and sizes, fishes also come in such an amazing variety of shapes and sizes that there is no ‘typical’ fish skeleton, So the Fishbone can be of any shape and size.
When should a Fishbone Diagram be used?
- To get a holistic and logical representation of a problem broken down into a pictorial format.
- To study a problem/issue and to determine the root cause?
- To study all the possible reasons why a process is beginning to have difficulties, problems, or breakdowns?
- To Arrive at a Solution to any problem.
- To Simplify a process flow.
- To study why a process is not performing efficiently or producing the desired results?
Time required will be approximately half an hour to 6 Hrs, depending upon the problem and how deep you would like to analyze the problem.
This method can be used in a team of 8 to 14 people to identify the root cause of the problem. You can take a look at my fishbone diagram case study.
Steps to Construct a Fishbone Diagram
- List the problems/issues to be studied in the “head of the fish”.
- Label each “bone” of the “fish”. The major categories typically utilized are:
- In a manufacturing situation you can use the 6M’s as branch headings(or Bone Headings) to get you started.
- Machines, Methods, Materials, Measurement, Man and Mother Nature (the environment)
- In an office environment you can use the 8P’s.
- Price, Promotion, People, Processes, Place, Policies, Procedures, Product.
- Or The 4S’s:
- Surroundings, Suppliers, Systems, Skills.
-
4. You may use one of the above suggested categories or combine them in any fashion or make up your own. The categories are basically to help you organize your ideas.
- Use an idea-generating technique (e.g. brainstorming) to identify the factors within each category that may be affecting the problem/issue or effect being studied.
- Repeat this procedure with each factor under the category to produce sub-factors. Continue asking, “Why is this happening?” and put additional segments each factor and subsequently under each sub-factor.
- Continue until you no longer get useful information as you ask, “Why is that happening?”
- Analyze the results of the cause effect diagram after team members agree that an adequate amount of detail has been provided under each major category. Do this by looking for those items that appear in more than one category. These become the ‘most likely causes”.
5. For those items identified as the “most likely causes“, the team should reach consensus on listing those items in priority order with the first item being the “most probable” cause.
5WHYs
nWHY 1 :Why my car had stopped ?
nNo petrol in tank
nWHY 2 :Why i did not have a petrol in my tank ?
nI did not buy in the morning
on my way to work
nWHY 3 :Why i did
not buy a petrol ?
nNo money in my pockets
nWHY 4 : Why no money i my
pockets?
nEvening poker
nWHY 5 : Why i did not win a poker game?
nI do not know how to
bluff!
- Machines, Methods, Materials, Measurement, Man and Mother Nature (the environment)
- Price, Promotion, People, Processes, Place, Policies, Procedures, Product.
- Surroundings, Suppliers, Systems, Skills.
-
nWHY 1 :Why my car had stopped ?
nNo petrol in tank
nWHY 2 :Why i did not have a petrol in my tank ?
nI did not buy in the morning
on my way to work
nWHY 3 :Why i did
not buy a petrol ?
nNo money in my pockets
nWHY 4 : Why no money i my
pockets?
nEvening poker
nWHY 5 : Why i did not win a poker game?
nI do not know how to
bluff! 
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