A review of factor modification methods in human reliability analysis

Frequent accidents caused by human factors in different industrial fields indicate that human reliability analysis (HRA) plays an important role in reducing and preventing human errors and thereby improving the reliability of human-machine system. Different from the mathematical model which can solve the precise in system reliability analysis, HRA focuses on the operator´s erroneous actions and task context, this determines that human reliability should be analyzed by combining qualitative and quantitative methods. In order to objectively quantify human behavior and task context by HRA results, modifying factors are usually adopted to quantify the final human error probability (HEP) based on the qualitative analysis of the operator´s erroneous actions and task context. A complete factor modification method consists of modifying factor selection, factor modification strategy and factor modification mechanism (mathematical logic of how the modifying factors influence HEP). In this paper, based on the analysis of connotation and selection of modifying factors in HRA methods and according to the distinctions among factor modifying objects in human reliability quantitative assessment, three kinds of factor modification strategies are generalized from factor modification methods in existing HRA methods and detailedly analyzed and reviewed as well, namely systemic-parameter-based, cognitive-behavior-based and simulation-based factor modification strategies. Meanwhile, the factor modification mechanism in before-mentioned factor modification methods are analyzed and summarized.