Why–because analysis
Why–because analysis (WBA) is a method for accident analysis. It is independent of application domain and has been used to analyse, among others, aviation-, railway-, marine-, and computer-related accidents and incidents. It is mainly used as an after the fact (or a posteriori) analysis method. WBA strives to ensure objectivity, falsifiability and reproducibility of results.
The result of a WBA is a why–because graph (WBG). The WBG depicts causal relations between factors of an accident. It is a directed acyclic graph where the nodes of the graph are factors. Directed edges denote cause–effect relations between the factors.
WBA in detail
WBA starts with the question "What is the accident or accidents in question?". In most cases this is easy to define. Next comes an iterative process to determine causes. When causes for the accident have been identified, formal tests are applied to all potential cause-effect relations. This process can be iterated for the newfound causes, and so on, until a satisfactory result has been achieved.