A Taxonomy of Error Types for Failure Analysis and Risk Assessment

We describe a taxonomy of error types that builds on work by Reason (1990) and Hollnagel (1993). The taxonomy uses a faceted schema subdivided into layers. Each layer targets a particular analysis task, and a method is proposed leading the assessor through sets of error types at different levels (e.g. cognitive, social, organizational). This allows the causes of failure to be attributed to one or more error types. The method is illustrated with two case studies of diverse failures. The utility of taxonomy analysis in understanding the reasons for failure and risk assessment is discussed.