Cause and Effect Diagram     
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ã Copyright ASQ. Following article was published in Quality Progress Magazine, June 2000 Issue, One Good Idea Column.

Getting the Most from Cause and Effect Diagrams

By Timothy J. Clark

Editor’s Note: The following article expands on an idea briefly mentioned in the book Success Through Quality: Support Guide for the Journey to Continuous Improvement, written by Timothy J. Clark and published by ASQ Quality Press (item H1006).

The cause and effect diagram was developed by Kaoru Ishikawa in 1943 and is one of the seven basic tools of quality. The tool helps identify and document the causes and subcauses of a specific problem or effect (see Figure 1). The assumption is that if one or more causes of a problem are eliminated or reduced, then quality will be improved.

Figure 1 Cause and Effect Diagram for a Test in School

 

A cause and effect diagram can be enhanced, however, by following up with a responsibility matrix and an action planning matrix. A responsibility matrix identifies the degree of control the process owners have over the respective cause and the action that could be taken to reduce or eliminate the problem. The action planning matrix acts as a final step for taking action and assessing results.

The responsibility matrix

The responsibility matrix identifies who within the system has ownership over the cause, as well as the degree of control that person has to eliminate or reduce the effects of the cause.

When developing a responsibility matrix, begin by listing the causes and provide a short description of each, including any subcauses. Next, identify the process owners and the degree of control they have over the respective cause. Control can be broken down into three degrees: direct, some or little. Finally, document the action to be taken. A completed responsibility matrix using three of the causes listed in Figure 1 is provided in Figure 2.

Figure 2 Responsibility Matrix

 

Causes

 

Description

Process owner(s)

Degree of control

 

Action to be taken

 

Textbooks

Textbook selection

Superintendent

Direct

Survey current customers

Better textbooks are available

Teacher

Some

Suggest a change

 

Homework

 

Not enough assignments

Teacher

Direct

Assign more homework

Don’t understand the assignment

Student

Direct

Ask questions

Computers

Not enough computers

Board of education

Some

Request change in budget priorities

Not enough useful software

Teacher

Little

Recommend better software

 

The planning matrix

Once responsibilities and actions are determined, the next step is to complete a planning matrix (see Figure 3). This matrix includes the action to be taken and the expected result, the individual taking the action (who), when the action is to be completed and the necessary resources.

Figure 3: Action Planning Matrix

Action to be taken/expected result

Who

When

Resources

Textbook

Write letter suggesting that teachers provide input into textbook selection/acknowledgement of letter.

 

Teacher

 

30 days

 

Pen and paper

Homework

Assign more homework/improved test scores.

 

Teacher

 

3 days

 

Textbook and assignment sheets

Computers

Recommend software/

improved computer literacy and test scores.

 

Teacher

 

90 days

 

Pen and paper

 

The benefits of these matrices in supplementing the cause and effect diagram is that they help demonstrate and communicate the interdependencies and degree of control among stakeholders, help coordinate and align improvement actions, identify who will participate, and help illustrate that action can be taken despite the level of control.

 

Timothy J. Clark is a systems accountant for the department of defense finance and accounting service-Indianapolis Center. He earned his master’s degree in public administration from Ball State University in Muncie, IN. Clark is an ASQ certified quality auditor and an ASQ Senior Member.