Risk Perception: Searching for the Truth Among all the Numbers

  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.ch8

Managing Risk: The Human Element

Managing Risk: The Human Element

How to Cite

Duffey, R. B. and Saull, J. W. (2008) Risk Perception: Searching for the Truth Among all the Numbers, in Managing Risk: The Human Element, John Wiley & Sons, Ltd, Chichester, UK. doi: 10.1002/9780470714461.ch8

Author Information

  1. 1

    Atomic Energy of Canada (AECL), Canada

  2. 2

    International Federation of Airworthiness (IFA), UK

  1. The notion of measuring and replacing arbitrary risk perception was expounded in R.B. Duffey, The Prediction of Risk: Replacing Paranoia with Probability, Proc. 29th ESReDA Seminar on Systems Analysis for a More Secure World, Ispra, Italy, 25–26 October 2005; and of experience depth was described in R.B. Duffey and J.W. Saull, The Probability of System and Organizational Failure: Human Error and the Influence of Depth of Experience, Proc. International Topical Meeting on Probabilistic Safety Analysis (PSA 05), San Francisco, CA, 11–15 September 2005.

Publication History

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

ISBN Information

Print ISBN: 9780470699768

Online ISBN: 9780470714461



  • homo-technological system (HTS);
  • Universal Learning Curve (ULC);
  • risk perception - searching for truth;
  • Statistical Error State Theory (SEST);
  • outcomes - number and distribution;
  • coal mining and risk perception;
  • quality control and assurance (QA and QC);
  • fitting a learning curve


This chapter contains sections titled:

  • Perceptions and Predicting the Future: Risk Acceptance and Risk Avoidance

  • Fear of the Unknown: The Success Journey into What We Do or Do Not Accept

  • A Possible Explanation of Risk Perception: Comparisons of Road and Rail Transport

  • How Do We Judge the Risk?

  • Linking Complexity, Order, Information Entropy and Human Actions

  • Response Times, Learning Data and the Universal Laws of Practice

  • The Number and Distribution of Outcomes: Comparison to Data

  • Risk Perception: Railways

  • Risk Perception: Coal Mining

  • Risk Perception: Nuclear Power in Japan

  • Risk Perception: Rare Events and Risk Rankings

  • Predicting the Future Number of Outcomes

  • A Worked Example: Searching out and Analysing Data for Oil Spills

  • Typical Worksheet

  • Plotting the Data

  • Fitting a Learning Curve

  • Challenging Zero Defects

  • Comparison of Oil Spills to Other Industries

  • Predicting the Future: the Probability and Number of Spills

  • Observations on this Oil Spill Case

  • Knowing What We Do Not Know: Fear and Managing the Risk of the Unknown

  • White and Black Paradoxes: Known Knowns and Unknown Unknowns

  • The Probability of the Unknowns: Learning from What We Know

  • The Existence of the Unknown: Failures in High Reliability Systems

  • The Power of Experience: Facing Down the Fear of the Unknown

  • Terrorism, Disasters and Pandemics: Real, Acceptable and Imaginary Risks

  • Estimating Personal Risk of Death: Pandemics and Infectious Diseases

  • Sabotage: Vulnerabilities, Critical Systems and the Reliability of Security Systems

  • What Is the Risk?

  • The Four Quadrants: Implications of Risk for Safety Management Systems

  • References