Periodicity.: March - April 2019
e-ISSN......: 2236-269X
Cover Image

Identification and characterization of "Black Swans" in technological events in Brazil

Moacyr Machado Cardoso Junior


“Black swan” events represent a critical issue in risk analysis. Events with extremely low probability of occurrence are in general discarded from the risk analysis process. This paper aims to identify and characterize four accidents that occurred in Brazil into the following classes: “not a black swan”, “black swan: unknown-unknown”, “black swan: unknown-known” and “black Swan: not believed to occur”, by obtaining from experts the distribution of belief for the real probability of each class. Results showed that, throughout all cases analyzed, the class “black swan: unknown-unknown” was never reported, which means that none of the cases studied were a complete surprise to anyone. The method used was able to assign all accident events to the remaining classes. Probability distribution elicited from experts showed large disagreement among them, and the expected value was considered low. Nevertheless, the elicited distributions can be utilized in future risk analysis as a priori distribution in a Bayesian approach.


Black Swan; Expert elicitation; Technological accidents; Risk analysis.

Full Text:



ABNT-ISO. (2009) NBR-ISO 31000: Gestão de Riscos – Princípios e Diretrizes.

ASPINALL, W. P. (2005) Chapter 2 Structured Elicitation of Expert Judgment for Probabilistic Hazard and Risk Assessment in Volcanic Eruptions. In Mader, H.M.; et al. (Eds.), Statistics in volcanology. Special Publication of IAVCEI (p. 1–31) Geological Society of London.

AVEN, T. (2013) On the meaning of a black swan in a risk context. Safety Science, v. 57, p. 44–51. Available:

AVEN, T. (2015) Implications of black swans to the foundations and practice of risk assessment and management. Reliability Engineering and System Safety, v. 134. Available:

BOJKE, L.; CLAXTON, K.; BRAVO-VERGEL, Y.; SCULPHER, M.; PALMER, S.; ABRAMS, K. (2010) Eliciting distributions to populate decision analytic models. Value in Health, v. 13, n. 5, p. 557–564. Available:

BURGMAN, M.; FIDLER, F.; MCBRIDE, M.; WALSHE, T.; WINTLE, B. (2006) ACERA Project 0611 Eliciting Expert Judgments. Risk Analysis, v. 1 p. 71.

CLEMEN, R. T. (2008) Comments: Comment on Cooke’s classical method. Reliability Engineering and System Safety, v. 93, n. 5, p. 760–765. Available:

FLAGE, R.; AVEN, T. (2015) Emerging risk – Conceptual definition and a relation to black swan type of events. Reliability Engineering & System Safety, v. 144 (August) Available:

FOLHA DE SÃO PAULO. (2007) Entenda como aconteceu o desabamento nas obras do metrô em SP. São Paulo. Retrieved from

G1. (2016a) Justiça inocenta 14 réus por cratera que matou 7 no metrô de São Paulo. São Paulo. Retrieved from

G1. (2016b) MP divulga laudo e pede multa de R$ 3,6 bilhões por incêndio na Ultracargo. G1. Santos. Retrieved from

GARTHWAITE, P. H.; KADANE, J. B.; HAGAN, A. O. (2005) Statistical Methods for Eliciting Probability Distributions. Journal of the American Statistical Association, v. 100, n. 470, p. 680–701.

HOSACK, G. R.; HAYES, K. R.; BARRY, S. C. (2017) Prior elicitation for Bayesian generalised linear models with application to risk control option assessment. Reliability Engineering and System Safety, n. 167, p. 351–361.

IOANNOU, I.; ASPINALL, W.; RUSH, D.; BISBY, L.; ROSSETTO, T. (2017) Expert judgment-based fragility assessment of reinforced concrete buildings exposed to fire. Reliability Engineering and System Safety, n. 167, p. 105–127.

MACDONALD, J. A.; SMALL, M. J.; MORGAN, M. G. (2008) Explosion probability of unexploded ordnance: Expert beliefs. Risk Analysis, v. 28, n. 4, p. 825–841.

MORRIS, D. E.; OAKLEY, J. E.; CROWE, J. A. (2014) A web-based tool for eliciting probability distributions from experts. Environmental Modelling and Software, v. 52, p. 1–4.

OAKLEY, J. (2017) SHELF: Tools to Support the Sheffield Elicitation Framework. Retrieved from

OLIVEIRA, N.; (2016) Crea-RJ: falha de projeto é uma das causas do desabamento da Ciclovia Tim Maia. EBC Agência Brasil. Rio de janeiro. Retrieved from

Paté-Cornell, E. (2012) On “Black Swans” and “Perfect Storms”: Risk Analysis and Management When Statistics Are Not Enough. Risk Analysis, v. 32, n. 11, p. 1823–1833.

R DEVELOPMENT CORE TEAM. (2017) R: A Language and Environment for Statistical Computing. Vienna, Austria: R Foundation for Statistical Computing. Retrieved from

Taleb, N. N. (2010) The Black Swan: The Impact of the Highly Improbable (2nd ed.) Random House.

UOL. (2016) Trecho de ciclovia inaugurada em janeiro desaba no Rio. São Paulo. Retrieved from

USHER, W.; STRACHAN, N. (2013) An expert elicitation of climate, energy and economic uncertainties. Energy Policy, v. 61, p. 811–821. Available:


Article Metrics

Metrics Loading ...

Metrics powered by PLOS ALM


  • There are currently no refbacks.

Copyright (c) 2019 Moacyr Machado Cardoso Junior

Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.


Logo Gaudeamus






Logo Kennedy

Logo Columbia

Logo UCS


Logo OPT

Logo Biblioteca Professor Milton Cabral Moreira

Logo UFL