The Peltzman Effect & Risk Compensation

Peltzman effect is a theory which states that people tend to increasingly engage in risky behaviours once a security measure has been mandated. This effect is named after Sam Peltzman, an economist who postulated the theory with the use of seatbelts in automobiles.

The original context of the theory was the regulation of risk as the government tries to make things safer by issuing new regulations. Peltzman used auto safety as a case study, where the government made people wear seatbelts and also regulated various other features in the manufacturing of automobiles, such as pop-out windshields and other protective devices which are meant to make us safer.

The Economics of Risk

According to economic theory, when you make things cheaper then you will get more of them.  This is what led to Peltzman postulating that when you make a car safer in this way, drives will adjust their behaviour in response to the perceived level of risk.

In other words, if driving becomes safer, the drivers will become riskier when driving. Hence, the increase in safety measures will be compensated by riskier behaviour. This is what economists call Risk Compensation. In the case of auto safety, Peltzman predicted that the increase in risk behaviour would lead to more accidents, that would partly or completely offset the safety benefits of the regulation.

Later, Peltzman performed a study to see what the effects of the first generation of automobile safety regulations were auto-related accidents. The study did not focus on the first order effect (driver safety) but on the global effect (did more people survive on the road or did the automobile death rate goes down).

Risk Homeostasis

The conclusion of the study was that there was no effect on the death rate but there was a reduction in the probability that you would die in an accident which is the main purpose of the device. However, this benefit was completely offset by more accidents and many accidents involve people who weren’t in cars that are protected.

The Peltzman effect shows that people tend to drive recklessly and with less attention since they felt safer in the car which leads to more accidents than when these safety devices came out. The ratio of fatalities in accident went down but there was an increase in the accident which offset the decreased fatality rate.

He then concluded that if government regulates risk or anything, there is going to be an incentive created for behaviours that offset some part of what the government is trying to regulate and it could be a complete, partial, or more than complete offset. And the main thing that this regulation does is that it makes the consequences of an accident less severe.

Examples of Risk Compensation

Although the Peltzman study used the auto safety regulations as an example of risk compensation, this phenomenon has been observed in a range of activities. A few examples would be:

  • The use of helmets in skiing, snowboarding and rollerblades has been observed to increase risky behaviour.
  • A popular aphorism amongst skydivers, named Booth’s rule nr. 2 states that the safer skydiving gear becomes, the more chances skydivers will take constant

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Gísli Eyland

There are just too many interesting things going on

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