A micromort (from micro- and mortality) is a unit of risk defined as a one-in-a-million chance of death.[1][2] Micromorts can be used to measure the riskiness of various day-to-day activities. A microprobability is a one-in-a million chance of some event; thus, a micromort is the microprobability of death. The micromort concept was introduced by Ronald A. Howard who pioneered the modern practice of decision analysis.[3]

Micromorts for future activities can only be rough assessments, as specific circumstances will always have an impact. However, past historical rates of events can be used to provide a rough estimate.

Sample values

Baseline

Death from Context Time period N deaths N population Micromorts per unit of exposure Reference
All causes England and Wales 2012 499,331 56,567,000 24 per day
8,800 per year 		ONS Deaths[4] Table 5.
Canada 2011 242,074 33,476,688 20 per day
7,200 per year 		Statistics Canada[5]
US 2010 2,468,435 308,500,000 22 per day
8,000 per year 		CDC Deaths[6] Table 18.
Non-natural cause England and Wales 2012 17,462 56,567,000 0.8 per day
300 per year 		ONS Deaths[4] Table 5.19.
US 2010 180,000 308,500,000 1.6 per day
580 per year 		CDC Deaths[6] Table 18
Non-natural cause (excluding suicide) England and Wales 2012 12,955 56,567,000 0.6 per day
230 per year 		ONS Suicides[7]
US 2010 142,000 308,500,000 1.3 per day
460 per year 		CDC Deaths[6] Table 18.
All causes – first day of life England and Wales 2007 430 per first day of life Walker, 2014[8]
US 2013 16.7 per day
6100 per year 		CDC Life Tables[9]
Blastland & Spiegelhalter, 2014[10]
Murder/homicide England and Wales 2012/13 551 56,567,000 10 per year ONS Crime[11]
Homicide Canada 2011 527 33,476,688 15 per year Statistics Canada[12]
Murder and non-negligent manslaughter US 2012 14,173 292,000,000 48 per year FBI[13] Table 16

Leisure and sport

Death from Context Time period N deaths N exposure Micromorts per unit of exposure Reference
Scuba diving UK: BSAC members 1998–2009 75 14,000,000 dives 5 per dive BSAC[14]
UK: non-BSAC 1998–2009 122 12,000,000 dives 10 per dive BSAC[14]
US – insured members of DAN 2000–2006 187 1,131,367 members 164 per year as member of DAN
5 per dive 		DAN[15] p75
Paragliding Turkey 2004–2011 18 242,355 flights 74 per launch Canbek 2015[16]
Skiing US 2008/9 39 57,000,000 days skiing 0.7 per day Ski-injury.com[17][unreliable source]
Skydiving US 2000–2016 413 48,600,000 jumps 8 per jump USPA[18]
UK 1994–2013 41 4,864,268 jumps 8 per jump BPA[19]
BASE jumping Kjerag Massif, Norway 1995–2005 9 20,850 jumps 430 per jump Soreide 2007[20]
Mountaineering Ascent to Matterhorn 1981–2011 213 about 75,000 ascents

(about 2500 per year)

about 2,840 per ascent attempt Bachmann 2012[21]
Ascent to Mt. Everest 1922–2012 223 5,656 successful ascents 37,932 per successful ascent NASA 2013[22]

Travel

Activities that increase the death risk by roughly one micromort, and their associated cause of death:

Other

Increase in death risk for other activities on a per-event basis:

Value of a micromort

Willingness to pay

An application of micromorts is measuring the value that humans place on risk. For example, a person can consider the amount of money they would be willing to pay to avoid a one-in-a-million chance of death (or conversely, the amount of money they would receive to accept a one-in-a-million chance of death). When offered this situation, people claim a high number. However, when looking at their day-to-day actions (e.g., how much they are willing to pay for safety features on cars), a typical value for a micromort is around $50 (in 2009).[31][32] This is not to say the $50 valuation should be taken to mean that a human life (1 million micromorts) is valued at $50,000,000. Rather, people are less inclined to spend money after a certain point to increase their safety. This means that analyzing risk using the micromort is more useful when using small risks, not necessarily large ones.[32]

Value of a statistical life

Government agencies use a nominal Value of a Statistical Life (VSL) – or Value for Preventing a Fatality (VPF) – to evaluate the cost-effectiveness of expenditure on safeguards. For example, in the UK, the VSL is £1 million GBP in 1997 value (equivalent to £2 million in 2021[33]).[34] Since road improvements have the effect of lowering the risk of large numbers of people by a small amount, the UK Department for Transport essentially prices a reduction of 1 micromort at £1.60. The US Department of Transportation uses a VSL of US$6.2 million, pricing a micromort at US$6.20.[35]

Chronic risks

Micromorts are best used to measure the size of acute risks, i.e. immediate deaths. Risks from lifestyle, exposure to air pollution, and so on are chronic risks, in that they do not kill straight away, but reduce life expectancy. Ron Howard included such risks in his original 1979 work,[24] for example, an additional one micromort from:

Such risks are better expressed using the related concept of a microlife.

See also

Notes

  1. ^ however due to the health effects of cycling the net effect of cycling on life expectancy is likely positive in most cases[25]

References

  1. ^ Fry, A.M.; Harrison, A.; Daigneault, M. (February 2016). "Micromorts - what is the risk?". British Journal of Oral and Maxillofacial Surgery. 54 (2): 230–231. doi:10.1016/j.bjoms.2015.11.023. PMID 26747014.
  2. ^ Walker, KF; Cohen, AL; Walker, SS; Allen, KM; Baines, DL; Thornton, Jg (May 2014). "The dangers of the day of birth". BJOG. 121 (6): 714–718. doi:10.1111/1471-0528.12544. PMID 24521517. S2CID 24808758.
  3. ^ Howard, R. A. (1980). J. Richard; C. Schwing; Walter A. Albers (eds.). On making life and death decisions. Societal Risk Assessment: How Safe Is Safe Enough? General Motors Research Laboratories. New York: Plenum Press. ISBN 0306405547.
  4. ^ a b "Deaths Registered in England and Wales (Series DR), 2012" (PDF). Office for National Statistics. 22 October 2013. Archived (PDF) from the original on 6 June 2014. Retrieved 3 June 2014.
  5. ^ "Leading causes of death, by sex (Both sexes)". Statistics Canada. Archived from the original on 24 September 2015. Retrieved 14 August 2015.
  6. ^ a b c SL Murphy; J Xu & KD Kochanek (8 May 2013). "Deaths: Final Data for 2010" (PDF). US: Centers for Disease Control and Prevention. Archived (PDF) from the original on 11 May 2015. Retrieved 3 June 2014.
  7. ^ "Suicides in the United Kingdom, 2012 Registrations". Office for National Statistics. 18 February 2014. Archived from the original on 13 May 2014. Retrieved 11 June 2014.
  8. ^ KF Walker; AL Cohen; SH Walker; KM Allen; DL Baines; JG Thornton (13 February 2014). "The dangers of the day of birth". British Journal of Obstetrics and Gynaecology. 121 (6). London: Royal College of Obstetricians and Gynaecologists: 714–8. doi:10.1111/1471-0528.12544. PMID 24521517. S2CID 24808758.
  9. ^ "Life Tables". cdc.gov. [[Centers for Disease Control and Prevention]]. 2013. Archived from the original on 26 November 2013. Retrieved 24 November 2013.
  10. ^ Blastland, Michael; Spiegelhalter, David (2014). The Norm Chronicles: Stories and Numbers About Danger and Death (1 ed.). Basic Books. p. 14. ISBN 9780465085705.
  11. ^ "Crime Statistics, Focus on Violent Crime and Sexual Offences, 2012/13 – ONS". Office for National Statistics. 13 February 2014. Archived from the original on 8 April 2014. Retrieved 12 June 2014.
  12. ^ "Leading causes of death, total population, by age group and sex, Canada". Statistics Canada. 26 November 2020. Archived from the original on 3 July 2013. Retrieved 14 August 2015.
  13. ^ "Crime in the United States, 2012: Table 16". FBI. Federal Bureau of Investigation. Archived from the original on 29 May 2016. Retrieved 12 June 2014.
  14. ^ a b British Sub-Aqua Club. "UK Diving Fatalities Review". Archived from the original on 28 July 2014. Retrieved 12 June 2014.
  15. ^ Divers Alert Network (DAN). "Fatalities_Proceedings.pdf" (PDF). Archived (PDF) from the original on 16 January 2015. Retrieved 12 June 2014.
  16. ^ Canbek, Umut; Ahmet İmerci; Ulaş Akgün; Murat Yeşil; Ali Aydin; Yasemin Balci (1 September 2015). "Characteristics of injuries caused by paragliding accidents: A cross-sectional study". World Journal of Emergency Medicine. 6 (3): 221–224. doi:10.5847/wjem.j.1920-8642.2015.03.011. PMC 4566014. PMID 26401185.
  17. ^ Ski-injury.com. "Ski Injury". Archived from the original on 28 May 2014. Retrieved 12 June 2014.
  18. ^ United States Parachute Association. "Skydiving Safety". Archived from the original on 22 August 2018. Retrieved 10 April 2018.
  19. ^ British Parachute Association (2012). "How Safe". Archived from the original on 27 July 2014. Retrieved 12 June 2014.
  20. ^ Soreide, Kjetil; Ellingsen, Christian Lycke; Knutson, Vibeke (May 2007). "How Dangerous is BASE Jumping? An Analysis of Adverse Events in 20,850 Jumps From the Kjerag Massif, Norway". The Journal of Trauma: Injury, Infection, and Critical Care. 62 (5): 1113–1117. doi:10.1097/01.ta.0000239815.73858.88. PMID 17495709.
  21. ^ Bachmann, Stefan (September 2012). "Tod am Matterhorn" (PDF). Beobachter (in German).
  22. ^ "The World's Tallest Mountain". Earth Observatory. NASA. 2 January 2014. Archived from the original on 25 October 2014. Retrieved 25 October 2014.
  23. ^ a b c d e "Understanding Uncertainty". Plus Magazine. 12 July 2010. Archived from the original on 4 August 2020. Retrieved 22 July 2020.
  24. ^ a b c d e f g h i j k * Howard, Ron Risky Decisions (Slide show), Stanford University
  25. ^ de Hartog, Jeroen Johan; Boogaard, Hanna; Nijland, Hans; Hoek, Gerard (August 2010). "Do the Health Benefits of Cycling Outweigh the Risks?". Environmental Health Perspectives. 118 (8): 1109–1116. doi:10.1289/ehp.0901747. PMC 2920084. PMID 20587380.
  26. ^ "MDMA ('ecstasy'): a review of its harms and classification under the Misuse of Drugs Act 1971". London: Advisory Council on the Misuse of Drugs. 2009. p. 18. Archived from the original on 5 October 2012 – via Internet Archive.
  27. ^ Blastland, Michael; Spiegelhalter, David (2014). The Norm Chronicles: Stories and Numbers About Danger and Death (1 ed.). Basic Books. p. 8. ISBN 9780465085705.
  28. ^ a b Spiegelhalter, David; Blastland, Michael (30 May 2013). The Norm Chronicles: Stories and numbers about danger (Main ed.). London: Profile Books. ISBN 9781846686207.
  29. ^ Nina Weber, DER SPIEGEL (22 April 2021). "Coronaimpfung und Risikoabwägung: Einmal impfen ist weniger riskant als eine Woche Skiurlaub". Der Spiegel (in German). Archived from the original on 18 February 2022. Retrieved 11 June 2021.
  30. ^ Levin AT, Hanage WP, Owusu-Boaitey N, Cochran KB, Walsh SP, Meyerowitz-Katz G (December 2020). "Assessing the age specificity of infection fatality rates for COVID-19: systematic review, meta-analysis, and public policy implications". European Journal of Epidemiology. 35 (12): 1123–1138. doi:10.1007/s10654-020-00698-1. PMC 7721859. PMID 33289900. Text was copied from this source, which is available under a Creative Commons Attribution 4.0 International License Archived 16 October 2017 at the Wayback Machine.
  31. ^ Howard, R. A. (1989). "Microrisks for Medical Decision Analysis". International Journal of Technology Assessment in Health Care. 5 (3): 357–370. doi:10.1017/S026646230000742X. PMID 10295520. S2CID 37558060.
  32. ^ a b Russell, Stuart; Norvig, Peter (2009). Artificial Intelligence (3rd ed.). Prentice Hall. p. 616. ISBN 978-0-13-604259-4.
  33. ^ UK Retail Price Index inflation figures are based on data from Clark, Gregory (2017). "The Annual RPI and Average Earnings for Britain, 1209 to Present (New Series)". MeasuringWorth. Retrieved 11 June 2022.
  34. ^ "Unit A4.1: Social Impact Appraisal" (PDF). Transport analysis guidance. London: Department for Transport. January 2014. p. 6. ((cite book)): Unknown parameter |agency= ignored (help)
  35. ^ US Department of Transportation, "Treatment of the Economic Value of a Statistical Life in Departmental Analyses—2011 Interim Adjustment", 2011, http://www.dot.gov/policy/transportation-policy/treatment-economic-value-statistical-life Archived 2 November 2014 at the Wayback Machine
  36. ^ "Radiation dose issues and risk" (PDF). European Society of Radiology. Archived from the original (PDF) on 19 February 2014. Retrieved 18 November 2013.

Further reading

External links

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