The cause and effect diagram is one of the seven quality tools (7QC tools) used in the Plan-Do-Check-Act cycle to solve project management problems related to quality. In fact, it is the first basic quality tool indicated in the PDCA cycle.
Also called as the Ishikawa diagram, the cause and effect diagram looks like a fishbone. The problem statement is usually located at the head of the diagram which is used as the point in order to trace the root cause. The problem is often considered as the objective that needs to be achieved. Root causes are determined through the problem statement by asking “why”. A particular problem statement can have many root causes and they are placed in the diagram on each fishbone until everything has been exhausted.
This type of diagram is beneficial in connecting different effects that are deemed as a special variation to the cause. And each of the causes requires corrective actions to control the problem indicated in the statement. This tool is necessary for determining and exhausting the different underlying causes of a particular problem so that the appropriate corrective measures are delivered.
This project management term is defined in the 5th edition of the PMBOK.