Cause And Effect Analysis

Cause-and-effect diagram This popular diagram (also known as an Ishikawa diagram or fishbone diagram was developed in 1950 by the late Professor Kaoru Ishikawa. To create the diagram, the effect (symptom) is written at the head of the arrow. Potential causes (theories) are then added to complete the diagram. A common set of major categories of causes consists of personnel, work methods, materials, and equipment. Figure 5.14 shows the cause-and-effect diagram as prepared for the same list of theories as was arranged in Table 5.6. Note how the diagram aids in identifying interrelationships among theories. Cause-and-effect diagrams were first applied to manufacturing problems. They have since demonstrated that they are applicable to all manner of industries, processes, and problems. As a result, they are now in universal use in every conceivable application. A cause-and-effect diagram can be combined with a force-field analysis. The team identifies the situations and events that contribute to the problem (these are the “restraining forces”). The actions necessary to counter the restraining forces are then identified (these actions are the “driving forces”). Finally, a diagram combining the restraining and driving forces is prepared to assist in diagnosis.