Ishikawa Cause & Effect

Ishikawa Cause & Effect

I love this tool, a post by me.

The worlds most widely used Root Cause Analysis, RCA, tool. Kaoru Ishikawa developed the Fish Bone Diagram back in the 1960s while pioneering Quality Management processes in the Kawasaki shipyards. As a result of his work, he became one of the founding fathers of modern management programs.

Causes in the diagram are often categorized, such as to the 5 M's and E, described below. Cause-and-effect diagrams can reveal key relationships among various variables, and the possible causes provide additional insight into process behavior.

Causes can be derived from brainstorming sessions. These groups can then be labeled as categories of the fishbone. They will typically be one of the traditional categories mentioned above but may be something unique to the application in a specific case. Causes can be traced back to root causes with the “5 whys” technique.

The Basic Structure of the Fish Bone Diagram

The typical categories used are derived from Dr. W. Edwards Deming’s process inputs: Machines, Methods, Material, Manpower, Environment and Measurement, the 5 M's and E. Of course categories can be added or edited to match your system influencers. The following is an example of a diagram build.

Once the brainstorming session has exhausted all possible causes, we then need to pick the consensus root cause or causes.  I use a system of giving each member of the team 5 check marks. The member can use all 5 on one root cause that they think is the actual cause or they can give 3 to one and 2 to another as they feel fit. The root cause with the most check marks is the consensus root cause.

You could also use the common tool called the Nominal Group Technique.  In the NGT, the causes a listed and counted. So if you have 10 root causes, each member of the team ranks the causes in order of possibility. The most possible root cause would get 10 points the second probable cause would get 9 points and so on. The root cause with the most points would be the consensus root cause.

I suggest you get a copy of the NUMBER ONE Safety Management Systems tool book today. I encourage you to read more about the Ishikawa Fish bone diagram and also the following:

Brainstorming Techniques

Nominal Group Technique

The 5 Whys

            

Get the SMS Memory Jogger II at dtitraining.com 

The Ishikawa Fish Bone diagram has become one of the 7 Basic Quality Assurance Tools. It is important to have "TOOLS" to work with in making decisions, working with teams, and analysis of data. The Memory Jogger II is a great little pocket guide that thousands of already aquired and use on an on-going basis. Root Cause Analysis is an essential part of your QA and SMS.

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