The Probability of Human Error: Learning in Technological Systems

  1. Dr. Romney B. Duffey BSc, PhD, FASME scientist manager speaker Principal Scientist ASME Fellow past Chair active member1 and
  2. John W. Saull CEng, FRAeS, DAE aviation regulator executive director head member chairman2

Published Online: 31 OCT 2008

DOI: 10.1002/9780470714461.ch4

Managing Risk: The Human Element

Managing Risk: The Human Element

How to Cite

Duffey, R. B. and Saull, J. W. (2008) The Probability of Human Error: Learning in Technological Systems, in Managing Risk: The Human Element, John Wiley & Sons, Ltd, Chichester, UK. doi: 10.1002/9780470714461.ch4

Author Information

  1. 1

    Atomic Energy of Canada (AECL), Canada

  2. 2

    International Federation of Airworthiness (IFA), UK

  1. This Chapter builds in part on the paper R.B. Duffey and J.W. Saull, The Probability and Management of Human Error, Proc., 12th International Conference on Nuclear Engineering (ICONE 12), #49287, Crystal City, MD, 25–29 April 2004.

Publication History

  1. Published Online: 31 OCT 2008
  2. Published Print: 24 OCT 2008

ISBN Information

Print ISBN: 9780470699768

Online ISBN: 9780470714461



  • universal learning curve (ULC);
  • human error probability - technological system learning;
  • risk exposure definition and perfection level;
  • learning probabilities and PDF s;
  • MERE outcome probability;
  • MERE human error rate frequency;
  • maximum and minimum likelihood;
  • dynamic human error probability (HEP)


This chapter contains sections titled:

  • What We Must Predict

  • The Probability Linked to the Rate of Errors

  • The Definition of Risk Exposure and the Level of Attainable Perfection

  • Comparison to Conventional Social Science and Engineering Failure and Outcome Rate Formulations

  • The Learning Probabilities and the PDFs

  • The Initial Failure Rate and its Variation with Experience

  • The Best MERE Risk Values

  • Maximum and Minimum Likely Outcome Rates

  • Standard Engineering Reliability Models Compared to the MERE Result

  • Future Event Estimates: The Past Predicts the Future

  • Statistical Bayesian-Type Estimates: The Impact of Learning

  • Maximum and Minimum Likelihood

  • Comparison to Data: The Probability of Failure and Human Error

  • Comparison of the MERE Result to Human Reliability Analysis

  • Implications for Generalised Risk Prediction

  • Conclusions: The Probable Human Risk

  • References