Qualitative and quantitative evaluation of human error in risk assessment

This document has provided an overview of a framework for the assessment of human error in risk assessments. The main emphasis has been on the importance of a systematic approach to the qualitative modelling of human error. This leads to the identification and possible reduction of the human sources of risk. This process is of considerable value in its own right, and does not necessarily have to be accompanied by the quantification of error probabilities. Because of the engineering requirement to provide numerical estimates of human error probabilities in applications such as safety cases, examples of major quantification techniques have been provided, together with case studies illustrating their application. It must be recognised that quantification remains a difficult area, mainly because of the limitations of data. However, the availability of a systematic frame work within which to perform the human reliability assessment means that despite data limitations, a comprehensive treatment of human reliability can still yield considerable benefits in identifying, assessing and ultimately minimising human sources of risk.