Assessing dependency in SPAR-H: Some practical considerations

Abstract

Dependency, the relationship between a series of human errors, is an important factor to consider when conducting a human reliability analysis (HRA). The premise of this paper is that we should not expect dependency to be applied frequently. This paper presents guidance on the application of dependency in the SPAR-H HRA method. Overall guidance is provided to prevent overuse of dependency, and then eight specific insights are provided to ensure dependency is applied correctly. Without proper application of dependency, there is the risk that human error probabilities produced by HRA methods will be inaccurate. This paper seeks to ensure dependency does not lead to spurious quantification of errors.