1. Why and how to identify the causes of defects?

One of the pillars of a quality approach is system improvement, which involves, among other things, implementing actions to correct and prevent defects. The definition and implementation of relevant and effective actions of course depend on a good analysis of defects (understanding the problem) and identification of the causes at the origin of these defects.

The Ishikawa (or fishbone) diagram is a proposed method for tracing the causes of defects:

• structures thinking and thus helps to identify the "real" causes of defects or failures;

• is easy to implement and can therefore be applied routinely to identify the causes of defects in most cases;

• is a visual method ideally suited to group work at all levels of the hierarchy.