Good question, Judith. As mentioned previously, it's useful when you are looking for the root cause - and other contributing causes - of a problem.

The advantage of the fishbone diagram is that it is a very visual analysis. Just like the Five Whys, it identifies many possible causes for an effect or problem but it immediately - and visually - sorts ideas into useful categories. It also enables you to more easily identify if the root cause is found multiple times as it allows you to see all causes simultaneously. It's also good as a presentation tool, but can become visually cluttering if causes are complex.