Finding the cause of problems

Control charts (and other collected data) may indicate problems with a system. For example,

However, after detection of a problem, its cause must be identified in order to rectify it. This is usually a non-trivial exercise and the following tools often help.

Brainstorming

Continuous quality improvement is usually performed by a team, and a good way to get ideas is with a brainstorming session.

Cause-and-effect diagrams

After possible causes for a problem have been contributed in a brainstorming session, they can be structured in a cause-and-effect diagram.

Because of the shape of this diagram, it is often called a fishbone diagram.

This structuring of possible causes helps to focus attention on the most likely causes and on ones that may be altered in the 'Do' step in the Plan-Do-Check-Act cycle.