ATHEANA

A Technique for Human Event Analysis (ATHEANA) is a technique used in the field of human reliability assessment (HRA). The purpose of ATHEANA is to evaluate the probability of human error while performing a specific task. From such analyses, preventative measures can then be taken to reduce human errors within a system and therefore lead to improvements in the overall level of safety.
There exist three primary reasons for conducting a HRA; error identification, error quantification and error reduction. As there exist a number of techniques used for such purposes, they can be split into one of two classifications; first generation techniques and second generation techniques.
First generation techniques work on the basis of the simple dichotomy of ‘fits/doesn’t fit’ in the matching of the error situation in context with related error identification and quantification and second generation techniques are more theory based in their assessment and quantification of errors. ‘HRA techniques have been utilised in a range of industries including healthcare, engineering, nuclear, transportation and business sector; each technique has varying uses within different disciplines.
ATHEANA is used following the occurrence of an incident. The various drivers of an incident and the possible outcomes are categorised into one of the following groupings: organisational influences; performance shaping factors; error mechanisms; unsafe actions; human failure event; unacceptable outcome(s). The resultant model may indicate solutions to improve reliability, however there are no numerical aspects involved in the methodology used to construct the model. Due to this characteristic, the technique is thus not considered to be suitable for use in certain fields such as comparative design work or sensitivity analysis. The methodology of ATHEANA is not predictive but does serve as a diagnostic modelling tool. Furthermore, its lack of Human Error Probability (HEP) as an output is a marked difference of the method compared to first generation HRA methodologies. The outcome provided by ATHEANA identifies various human actions within a system while also eliciting many contextual situations within this system, which influence whether the action will be carried out successfully or will lead to failure.
Background.
ATHEANA is a post-incident Human Reliability Assessment (HRA) methodology developed by the US Nuclear Regulatory Commission in 2000. It was developed in the hope that certain types of human behaviour in nuclear plants and industries, which use similar processes, could be represented in a way in which they could be more easily understood. It seeks to provide a robust psychological framework to evaluate and identify Performance Shaping Factors (PSFs) - including organisational/environmental factors - which have driven incidents involving human factors, primarily with the intention of suggesting process improvement. Essentially it is a method of representing complex accident reports within a standardised structure, which may be easier to understand and communicate.
ATHEANA methodology.
There are seven basic steps to the ATHEANA methodology 
The formulation by which ATHEANA quantifies error is as follows:
where: