Risk compensation
Encyclopedia
In ethology
, risk compensation is an effect whereby individual people may tend to adjust their behavior
in response to perceived changes in risk. It is seen as self-evident that individuals will tend to behave in a more cautious manner if their perception of risk or danger increases. Another way of stating this is that individuals will behave less cautiously in situations where they feel "safer" or more protected.
s, associated with the use of safety features such as car
seat belt
s and climbing rope. The evidence is particularly compelling for the case of antilock braking systems. The existence of this balancing behaviour does not mean an intervention does not work; the effect could be less than, equal to, or even more than the true efficacy of the intervention, depending on how well the perceived efficacy matches actual efficacy - and this will differ from individual to individual. It is likely to be least when an intervention is imperceptible and greatest when an intervention is intrusive or conspicuous.
The theory grew largely out of investigations of road safety interventions. It was noted that some interventions had failed to achieve the forecast savings in lives and injuries (e.g. Adams' discussion of seatbelt legislation). Theorists speculated that while the studies demonstrated that the probability
of injury given a crash had reduced, the fact that the overall probability of injury was unchanged indicated that there must have been some change in the probability of crashing.
is to drive faster, follow closer and brake later, accounting for the failure of ABS to result in any measurable improvement in road safety. The studies were performed in Canada
, Denmark
and Germany
.
A study led by Fred Mannering, a professor of civil engineering
at Purdue University
supports risk compensation, terming it the "offset hypothesis".
closer, and came within 1 meter 23% more often, when a cyclist was wearing a helmet. Statements made in the report included: “The closer a driver is to the cyclist, the greater chance of a collision.”, “Drivers passed closer to the rider the further out into the road he was.”, “The bicyclist’s apparel affects the amount of clearance the overtaking motorist gives the bicyclist”. This research thus implies risk compensation, not among cyclists but among fellow road users. The issue of risk compensation among cyclists has been a central topic in the quite heated debate concerning effectiveness of helmet legislation.
published a paper, The efficacy of seatbelt legislation: A comparative study of road accident fatality statistics from 18 countries, Dept of Geography University College, London 1981 - published in 1982 by the Society of Automotive Engineers.http://www.geog.ucl.ac.uk/~jadams/PDFs/SAE%20seatbelts.pdf This showed that in the countries studied, which included states with and without seat belt laws, there was no correlation between the passing of seat belt legislation
and the total reductions in injuries or fatalities. When all associated fatalities and injuries in road accidents were included, it appeared that some accidents were being displaced from car drivers to pedestrians and other road users.
This paper was published at a time when Britain was considering a seat belt law, so the Department of Transport
commissioned a report into the issue. In the event the report's author, Isles, agreed with Adams' conclusions. The Isles Report was never published officially but a copy was leaked to the Press some years later. The law was duly passed and subsequent investigation showed some reduction in fatalities, the cause of which could not be conclusively stated, due to the simultaneous introduction of evidential breath testing.
Other research has taken groups of drivers, including those who did and did not habitually wear seat-belts, and measured the effect on driving style in the habitually unbelted. The drivers were found to drive faster and less carefully when belted.
However, a 2007 study used data available for the years 1985-2002 from the US' National Highway Traffic Safety Administration’s (2005) Fatal Accident Reporting System (FARS). This study included fatalities of all road accident victims, including car occupants, and measured them using a fixed-effects model. It concluded that between 1985 and 2002 there were "significant reductions in fatality rates for occupants and motorcyclists after the implementation of belt use laws", and that "seatbelt use rate is significantly related to lower fatality rates for the total, pedestrian, and all nonoccupant models even when controlling for the presence of other state traffic safety policies and a variety of demographic factors."
, states that "The safer skydiving gear becomes, the more chances skydivers will take, in order to keep the fatality rate constant". Even though skydiving equipment has made huge leaps forward in terms of reliability in the past two decades, and safety devices such as AADs
have been introduced, the fatality rate has stayed roughly constant since the early 1980s.http://web.archive.org/web/20030211051448/http://www.skydivenet.com/fatalities/fatalities_history.html This can largely be attributed to an increase in the popularity of high performance canopies, which fly much faster than traditional parachutes. High speed manoeuvres close to the ground have increased the number of landing fatalities in recent years,http://www.iit.edu/~kallend/skydive/fatalities.gif even though these jumpers have perfectly functioning parachutes over their heads.
argued that the risk compensation phenomenon could explain the failure of condom distribution programs to reverse HIV
prevalence. Dr Green says his ideas are motivated by empirical research, rather than by any moral or religious association with the Catholic Church. Green provided more detailed explanations of his views in an op-ed article for The Washington Post
and an extended interview with the BBC. This view is shared by other specialists.
. This extends risk compensation theory somewhat, although in practice the two terms are often used interchangeably.
Professor Gerald J. S. Wilde illustrates this by reference to the Swedish experience when they changed
from left- to right-hand drive in 1967.http://ip.bmjjournals.com/cgi/content/full/4/2/89 This was followed by a marked reduction in the traffic fatality rate, but the trend returned to its previous values after about 18 months. Drivers had responded to increased perceived danger by taking more care; as they became accustomed to the new regime, the additional care evaporated.
Risk compensation is now widely accepted, but risk homeostasis, which goes much further, has a much smaller following.
Ethology
Ethology is the scientific study of animal behavior, and a sub-topic of zoology....
, risk compensation is an effect whereby individual people may tend to adjust their behavior
Behavior
Behavior or behaviour refers to the actions and mannerisms made by organisms, systems, or artificial entities in conjunction with its environment, which includes the other systems or organisms around as well as the physical environment...
in response to perceived changes in risk. It is seen as self-evident that individuals will tend to behave in a more cautious manner if their perception of risk or danger increases. Another way of stating this is that individuals will behave less cautiously in situations where they feel "safer" or more protected.
Description
There is evidence that suggests that such an effect is seen in humanHuman
Humans are the only living species in the Homo genus...
s, associated with the use of safety features such as car
Automobile
An automobile, autocar, motor car or car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor...
seat belt
Seat belt
A seat belt or seatbelt, sometimes called a safety belt, is a safety harness designed to secure the occupant of a vehicle against harmful movement that may result from a collision or a sudden stop...
s and climbing rope. The evidence is particularly compelling for the case of antilock braking systems. The existence of this balancing behaviour does not mean an intervention does not work; the effect could be less than, equal to, or even more than the true efficacy of the intervention, depending on how well the perceived efficacy matches actual efficacy - and this will differ from individual to individual. It is likely to be least when an intervention is imperceptible and greatest when an intervention is intrusive or conspicuous.
The theory grew largely out of investigations of road safety interventions. It was noted that some interventions had failed to achieve the forecast savings in lives and injuries (e.g. Adams' discussion of seatbelt legislation). Theorists speculated that while the studies demonstrated that the probability
Probability
Probability is ordinarily used to describe an attitude of mind towards some proposition of whose truth we arenot certain. The proposition of interest is usually of the form "Will a specific event occur?" The attitude of mind is of the form "How certain are we that the event will occur?" The...
of injury given a crash had reduced, the fact that the overall probability of injury was unchanged indicated that there must have been some change in the probability of crashing.
Anti-lock brakes
There are at least three studies which show that drivers' response to antilock brakesAnti-lock braking system
An anti-lock braking system is a safety system that allows the wheels on a motor vehicle to continue interacting tractively with the road surface as directed by driver steering inputs while braking, preventing the wheels from locking up and therefore avoiding skidding.An ABS generally offers...
is to drive faster, follow closer and brake later, accounting for the failure of ABS to result in any measurable improvement in road safety. The studies were performed in Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
, Denmark
Denmark
Denmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...
and Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
.
A study led by Fred Mannering, a professor of civil engineering
Civil engineering
Civil engineering is a professional engineering discipline that deals with the design, construction, and maintenance of the physical and naturally built environment, including works like roads, bridges, canals, dams, and buildings...
at Purdue University
Purdue University
Purdue University, located in West Lafayette, Indiana, U.S., is the flagship university of the six-campus Purdue University system. Purdue was founded on May 6, 1869, as a land-grant university when the Indiana General Assembly, taking advantage of the Morrill Act, accepted a donation of land and...
supports risk compensation, terming it the "offset hypothesis".
Bicycle helmets
A study published in the March 2007 issue of Accident Analysis & Prevention stated that drivers drove an average of 8.5 cmCentimetre
A centimetre is a unit of length in the metric system, equal to one hundredth of a metre, which is the SI base unit of length. Centi is the SI prefix for a factor of . Hence a centimetre can be written as or — meaning or respectively...
closer, and came within 1 meter 23% more often, when a cyclist was wearing a helmet. Statements made in the report included: “The closer a driver is to the cyclist, the greater chance of a collision.”, “Drivers passed closer to the rider the further out into the road he was.”, “The bicyclist’s apparel affects the amount of clearance the overtaking motorist gives the bicyclist”. This research thus implies risk compensation, not among cyclists but among fellow road users. The issue of risk compensation among cyclists has been a central topic in the quite heated debate concerning effectiveness of helmet legislation.
Ski helmets
“There is no evidence they reduce fatalities,” said Dr. Jasper Shealy, a professor from Rochester Institute of Technology who has been studying skiing and snowboarding injuries for more than 30 years. “We are up to 40 percent usage but there has been no change in fatalities in a 10-year period.” There is evidence that helmeted skiers tend to go faster.Seat belts
In 1981 John AdamsJohn Adams (geographer)
Professor John Adams of University College London, is a professor of geography and leading theorist on risk compensation and an environmentalist...
published a paper, The efficacy of seatbelt legislation: A comparative study of road accident fatality statistics from 18 countries, Dept of Geography University College, London 1981 - published in 1982 by the Society of Automotive Engineers.http://www.geog.ucl.ac.uk/~jadams/PDFs/SAE%20seatbelts.pdf This showed that in the countries studied, which included states with and without seat belt laws, there was no correlation between the passing of seat belt legislation
Seat belt legislation
Seat belt legislation requires the fitting of seat belts to motor vehicles and/or the wearing of seat belts by motor vehicle occupants. The U.S. state of Wisconsin introduced legislation in 1961 requiring front seat belt anchorages to be fitted to cars. The Australian state of Victoria mandated...
and the total reductions in injuries or fatalities. When all associated fatalities and injuries in road accidents were included, it appeared that some accidents were being displaced from car drivers to pedestrians and other road users.
This paper was published at a time when Britain was considering a seat belt law, so the Department of Transport
Department for Transport
In the United Kingdom, the Department for Transport is the government department responsible for the English transport network and a limited number of transport matters in Scotland, Wales and Northern Ireland which are not devolved...
commissioned a report into the issue. In the event the report's author, Isles, agreed with Adams' conclusions. The Isles Report was never published officially but a copy was leaked to the Press some years later. The law was duly passed and subsequent investigation showed some reduction in fatalities, the cause of which could not be conclusively stated, due to the simultaneous introduction of evidential breath testing.
Other research has taken groups of drivers, including those who did and did not habitually wear seat-belts, and measured the effect on driving style in the habitually unbelted. The drivers were found to drive faster and less carefully when belted.
However, a 2007 study used data available for the years 1985-2002 from the US' National Highway Traffic Safety Administration’s (2005) Fatal Accident Reporting System (FARS). This study included fatalities of all road accident victims, including car occupants, and measured them using a fixed-effects model. It concluded that between 1985 and 2002 there were "significant reductions in fatality rates for occupants and motorcyclists after the implementation of belt use laws", and that "seatbelt use rate is significantly related to lower fatality rates for the total, pedestrian, and all nonoccupant models even when controlling for the presence of other state traffic safety policies and a variety of demographic factors."
Skydiving
Booth's rule #2, coined by skydiving pioneer Bill BoothBill Booth
Bill Booth is an engineer, inventor, serious beard aficionado and entrepreneur in the skydiving equipment manufacturing industry. His invention of the 3-ring release safety device greatly enhanced skydiving safety. This device allows the rapid release of the skydiver's main parachute in the event...
, states that "The safer skydiving gear becomes, the more chances skydivers will take, in order to keep the fatality rate constant". Even though skydiving equipment has made huge leaps forward in terms of reliability in the past two decades, and safety devices such as AADs
Automatic activation device
Automatic Activation Device in skydiving terminology refers to an electronic-pyrotechnic or mechanical device that automatically opens the main or reserve parachute container at a preset altitude or after a preset time....
have been introduced, the fatality rate has stayed roughly constant since the early 1980s.http://web.archive.org/web/20030211051448/http://www.skydivenet.com/fatalities/fatalities_history.html This can largely be attributed to an increase in the popularity of high performance canopies, which fly much faster than traditional parachutes. High speed manoeuvres close to the ground have increased the number of landing fatalities in recent years,http://www.iit.edu/~kallend/skydive/fatalities.gif even though these jumpers have perfectly functioning parachutes over their heads.
Speed limits
A 1994 study by Jeremy Jackson and Roger Blackman, using a driving simulator, showed that although increased speed limits and reduced speeding fines significantly increased driving speed, there was no effect on accident frequency. It also showed that increased accident cost caused large and significant reductions in accident frequency but no change in speed choice. The abstract states that the results suggest that regulation of specific risky behaviors such as speed choice may have little influence on accident rates.Safety equipment in children
Experimental studies have suggested that children who wear protective equipment are likely to take more risks.Use of condoms in AIDS prevention
Harvard researcher Edward C. GreenEdward C. Green
Edward C. Green is an American medical anthropologist currently affiliated with the Dept. of Population and Reproductive Health, Johns Hopkins University. He was a Senior Research Scientist at the Harvard School of Public Health and served as director of the AIDS Prevention Research Project at...
argued that the risk compensation phenomenon could explain the failure of condom distribution programs to reverse HIV
HIV
Human immunodeficiency virus is a lentivirus that causes acquired immunodeficiency syndrome , a condition in humans in which progressive failure of the immune system allows life-threatening opportunistic infections and cancers to thrive...
prevalence. Dr Green says his ideas are motivated by empirical research, rather than by any moral or religious association with the Catholic Church. Green provided more detailed explanations of his views in an op-ed article for The Washington Post
The Washington Post
The Washington Post is Washington, D.C.'s largest newspaper and its oldest still-existing paper, founded in 1877. Located in the capital of the United States, The Post has a particular emphasis on national politics. D.C., Maryland, and Virginia editions are printed for daily circulation...
and an extended interview with the BBC. This view is shared by other specialists.
Risk homeostasis
An associated theory is known as risk homeostasisRisk homeostasis
Risk homeostasis is a hypothesis about risk, developed by Gerald J.S. Wilde, a professor emeritus of psychology at Queen's University, Kingston, Ontario, Canada. This hypothesis is elucidated in Wilde's book. The idea of risk homeostasis has garnered criticism. The hypothesis of risk homeostasis...
. This extends risk compensation theory somewhat, although in practice the two terms are often used interchangeably.
Professor Gerald J. S. Wilde illustrates this by reference to the Swedish experience when they changed
Dagen H
Dagen H , today mostly called "Högertrafikomläggningen" , was the day, 3 September 1967, on which traffic in Sweden switched from driving on the left-hand side of the road to the right...
from left- to right-hand drive in 1967.http://ip.bmjjournals.com/cgi/content/full/4/2/89 This was followed by a marked reduction in the traffic fatality rate, but the trend returned to its previous values after about 18 months. Drivers had responded to increased perceived danger by taking more care; as they became accustomed to the new regime, the additional care evaporated.
Risk compensation is now widely accepted, but risk homeostasis, which goes much further, has a much smaller following.
See also
- Moral hazardMoral hazardIn economic theory, moral hazard refers to a situation in which a party makes a decision about how much risk to take, while another party bears the costs if things go badly, and the party insulated from risk behaves differently from how it would if it were fully exposed to the risk.Moral hazard...
- Peltzman effectPeltzman EffectThe Peltzman effect is the hypothesized tendency of people to react to a safety regulation by increasing other risky behavior, offsetting some or all of the benefit of the regulation...
- Risk homeostasisRisk homeostasisRisk homeostasis is a hypothesis about risk, developed by Gerald J.S. Wilde, a professor emeritus of psychology at Queen's University, Kingston, Ontario, Canada. This hypothesis is elucidated in Wilde's book. The idea of risk homeostasis has garnered criticism. The hypothesis of risk homeostasis...
- Seat belt legislationSeat belt legislationSeat belt legislation requires the fitting of seat belts to motor vehicles and/or the wearing of seat belts by motor vehicle occupants. The U.S. state of Wisconsin introduced legislation in 1961 requiring front seat belt anchorages to be fitted to cars. The Australian state of Victoria mandated...
External links
- 'Naked' streets are safer, say Tories - The TimesThe TimesThe Times is a British daily national newspaper, first published in London in 1785 under the title The Daily Universal Register . The Times and its sister paper The Sunday Times are published by Times Newspapers Limited, a subsidiary since 1981 of News International...