Understanding how and why an event happened is the first step towards reducing the rate and impact of accidents. Most accidents can be prevented by doing something differently. Taking a structured approach to an incident investigation makes it much more likely that root causes will be identified and corrected, rather than simply blaming a problem on the actions of individuals. The practice of incident analysis and continual improvement has been behind the remarkable reduction in accident rates achieved in aviation and construction over the past decades. Medicine has a long way to go to reduce rates anywhere close to those achieved in these high-risk industries, and background figures showing this are presented in Chapter 3.