Signal Detection Theory: Enabling Work Near the Edge

T.S. Abdelhamid1, B. Patel2, G.A. Howell3 & P. Mitropoulos4

1Assistant Professor, 207 Farrall Hall, Construction Management Program, Michigan State University, East Lansing, MI 48824-1323. Email:
2Graduate Student Research Assistant, 9 Farrall Hall, Construction Management Program, Michigan State University, East Lansing, MI 48824-1323. Email:
3Executive Director, Lean Construction Institute, Box 1003, Ketchum, ID 83340. Email:
4PhD, Process Improvement Consultant, Menlo Park, CA 94025. Email:


Occupational accidents are unquestionably wasteful and non-value adding events in any system of production. Safeguarding construction workers from occupational hazards, whether arising from traumatic, ergonomic, and/or exposure accidents, is part and parcel of the lean construction ideal of waste elimination. Howell et al. (2002) proposed a new approach to understand construction accidents based on Rasmussen’s theory of cognitive systems engineering. One aspect of the model focused on worker training to recognize hazards (unsafe conditions). The underlying assumption here is that workers will always recall what constitutes a safe or unsafe situation as well as respond to perceived or actual risks in the same manner. Therefore, a methodology to assess worker sensitivity to unsafe conditions and risk orientation is needed. This paper proposes a methodology based on Signal detection theory that was originally developed as an assessment technique for tasks requiring the detection of defective components in an industrial setting. Discussion of signal detection theory and how it could be tailored for assessments of the sensitivity and risk orientation of construction workers to unsafe conditions is presented. Application of the methodology is demonstrated using a pilot study involving structural steel workers. The methodology presented in this paper could be used to give guidance to workers on how to enhance their abilities to identify the boundary beyond which work is no longer safe.


Occupational Safety, Construction Safety, Signal Detection Theory, Construction Accidents, Safety Training



Abdelhamid, T. , Patel, B. , Howell, G. & Mitropoulos, P. 2003, 'Signal Detection Theory: Enabling Work Near the Edge' In:, 11th Annual Conference of the International Group for Lean Construction. Virginia, USA, 1-.

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