MAP-01-011 HFI Technical Guide - Human Factors Integration ...

Annex 3 – HF Techniques, Methods and Tools• Disadvantages• The use of a Murphy Diagram as a predictive tool is unknown.• Could become large and unwieldy for large, complex tasks.• There is little guidance for the analyst.• Consistency of the method can be questioned.• Design remedies are based entirely upon the analyst’s subjectivejudgement.• It would be difficult to model time on a Murphy diagram.A3.10.5SHERPAThe Systematic Human Error Reduction and Prediction Approach (SHERPA) toolwas developed as a human error prediction technique that also enabled tasks tobe analysed and potential solutions to errors to be presented in a structuredmanner. The technique is based upon taxonomy of human error, and in itsoriginal form specified the psychological mechanism implicated in the error.The method utilises a eight stage process that is underpinned by a HierarchicalTask Analysis (HTA). On completion of a HTA, each identified task is classifiedusing a specified error taxonomy (Action, retrieval, checking, selection,information communication) upon which the analyst then identifies the credibleerror modes associated with each activity. Once the error modes have beendefined the analyst the considered the consequence of each error and whetherthe error could be recovered. The analyst then rates the probability of the erroroccurring based upon SME opinion and historical data. Following this, theanalyst defines whether the identified error is considered critical based upon theconsequence of occurrence. The final step is based upon developing suitableerror reduction strategies in he form of changes to the work system that couldhave prevented the error from occurring.The purpose of SHERPA is not only to identify potential errors with the currentdesign, but also to guide future design considerations. The structured nature ofthe analysis can help to focus the design remedies on solving problems.• Advantages• Structured and comprehensive procedure, yet maintains usability.• The SHERPA taxonomy prompts analyst for potential errors.• Encouraging validity and reliability data.• Substantial time economy compared to observation.• Error reduction strategies offered as part of the analysis, in addition topredicted errors.May 2006 Page A3-93 Issue 4