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4. The Cause & Effect Diagram

History of the Cause & Effect Diagram

The cause & effect diagram was first developed by Mr. Kaoru Ishikawa in the 1960s which is whyyoull often hear this tool referred to as the Ishikawa diagram.

But, due to its unique appearance, most simply refer to this tool as the fishbone diagram. And, in

case youre wondering, this is the same Mr. Ishikawa who popularized the 7 QC tools were studyingin this course.

Experiment and Make it Your Own

There are a number of different ways tocomplete a cause and effect matrix as such

wed encourage you to experiment and find the

approach that works best for you.

But to get you started Id like to share a roadmapwed encourage you to begin with.

First, youll want to get your cross-functional

team into the same room while also gathering all

the supplies needed. We recommend starting with post-it notes and a large piece of butcherspaperor a white board.

Write Problem Statement

After all the supplies are available, the first step is towrite the main problem or problemstatement being focused on the right side of the diagram while also drawing a box around it. We

then draw a long horizontal line and arrow off of this box representing the spine of the fish.

Draw in Major Cause Categories

After this were ready to draw in the major cause categories. Again, there are no right or

wrong major cause categories however a good place to start are the 4 to 6 Ms we learned about inour Practical Problem Solving course.

Now, for those in dealing with service related problems you might try the 6 Ps which stand forPeople, Process, Policies, Procedures, Price, and Product.

Develop List of Factors

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At this point its time for your team to get busy as you develop a list of factorsthat could be

causing or contributing to the problem. Again there are many ways to go about this.

One way I personally find effective is to hand out the same colored post it notes and pencils to all

team members. I then ask the question, Whats causing this problem? I then give everyone 3

to 5 minutes to write down as many ideas as they can on their post it notes, which is sometimesreferred to as the nominal group technique.

After 3 to 5 minutes I ask everyone to place their pencils down. I then go around and ask eachperson to share their results by reading them aloud. And as they read a post it note the team agrees

where it should be placed on the fishbone. And if it looks like a cause fits on more than one categorywe create a duplicate and place it in both places.

Once this initial brainstorming process is complete the discussion the team has had will usually drum

up additional ideas so I let the team write down additional causes followed by the same process of

reading them aloud and placing them on the fishbone accordingly.

You can actually repeat this process as many times as you need until it seems the team is out of ideas.The next step of the process is to create the second level of causes. To do this we go through each

post it note and ask, Why does this happen?

N/3

Once this process is complete well have identified numerous root causes possibly too many to

attack at once. So, at this point the team will need to select the root causes they wish to initiallyfocus on.

As youve probably guessed there are a number of ways to facilitate this process but one methodweve found to be effective is to seek out root causes that may be similar and group them together.

You should also use the same priority setting questions we learned about in an earlier module byassessing each root causes level of importance, urgency, and potential for expansion.

Also, depending on team dynamics you can also use a powerful technique called N over 3. To doN/3 you simply count up the number of root causes identified and divide that number by 3.

Identify Kaizen Bursts

Alright, well the last step of the fishbone creation process is to draw a cloud or kaizen burst symbolaround the root causes the team has selected to initially focus on keeping in mind that the fishbone

process is dynamic in nature meaning well definitely come back to update things as the team learnsmore and begins to attack additional problems.

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