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Why?

Understand why a problem occurs and prevent it from happening again.

How?

Systematically identify the possible factors that could have led to the problem. For each factor, determine whether it is symptom of a deeper cause. Classify the factors and define measures to prevent the problem from happening again. Do not stop too quickly; ensure that there is no deeper cause.

Ingredients

• A structured approach.
• No initial bias about possible causes or solutions.
• A diverse group of knowledge holders to help (e.g. security, software, business, user perspective).

In practice

Companies use many techniques (e.g. fishbone diagram, problem tree, 5x why). One example is a software company that put more and more effort into testing because of bad product quality. By using 5X Why, they discovered that the root cause was over-optimistic scheduling that led to stress for the developers.

Phase(s) of use

In the following project phase(s) root cause analysis can be used:

• Problem definition
• Analysis