Seat Belts and Saving Lives

From Wikipedia:

Professor John Adams of University College London was sceptical of such claims and set out to analyse the effect of seat belt laws as then in force and assess how well they matched predictions. His findings were published in 1982 and can be found in the Society of Automotive Engineers transactions of that year[5]. His conclusion was that in the eighteen countries surveyed, accounting for approximately 80% of the world’s motoring, those countries with seat belt laws had fared no better, and in some cases (e.g. Sweden, Ireland and New Zealand) significantly worse than those without.

In summarising the paradox, Adams agreed that :

The evidence that the use of a seat belt improves a car occupant’s chances of surviving a crash is convincing. That a person travelling at speed inside a hard metal shell will stand a better chance of surviving a crash if he is restrained from rattling about inside the shell is both intuitively obvious and supported by an impressive body of empirical evidence.[6]

In order to explain the disparity between the agreed improvement in a crash and the observed results, Adams advanced the hypothesis that protecting car occupants from the consequences of bad driving encourages bad driving.

He has suggested that a number of mechanisms are in play:

-Better protected drivers take less care (risk compensation or risk homeostasis).
-Case-control studies based on voluntary use of safety aids can attribute to the aid benefits that actually come from the risk-averse nature of those likely to use them voluntarily (confounding), particularly early adopters.
-Fatality rates are subject to considerable stochastic noise and comparison of single years or short periods can be misleading.

…

In response the UK’s Department of Transport commissioned a study on the effects of seat belt laws in Sweden, West Germany, Denmark, Spain, Belgium, Finland, the Netherlands and Norway. This study, known as “the Isles report” after its author, used the United Kingdom and Italy as controls for no-law countries compared casualty trends for both those inside and outside cars between law and no-law states. The report predicted that, based on the experiences of the eight countries studied, a UK seat belt law would be followed by a 2.3% increase in fatalities among car occupants [10] [11].

…

The Isles report was written by a civil servant in the Department of Transport. It did not back the pre-existing and still current position of Government, and it was never published.[10] [11] It is known mainly because it was leaked to The Spectator magazine some time after the law was passed.

The law mandating the compulsory wearing of seat belts for front seat occupiers came into force on January 31, 1983 in the UK[18]. Evidential breath testing was introduced at the same time.

There was a reduction in driver fatalities and an increase in fatalities of rear passengers (not covered by the law)[19]. A subsequent study of 19,000 cyclist and 72,000 pedestrian casualties seen at the time suggests that seat belt wearing drivers were 11-13% more likely to injure pedestrians and 7-8% more likely to injure cyclists

To simplify, seat belts make people feel safer in their vehicles. The safer they feel, the more aggressively they drive. Aggressive driving leads to more accidents, more pedestrian deaths and more injuries though the the likelihood of the aggressive driver getting hurt in an accident is reduced significantly. Compulsory seat belt laws have probably had no positive effect in reducing actual traffic related deaths.

Yes, the physics of car accidents would suggest wearing seat belts is a good idea. But the psychology of human behaviour suggests seat belt wearing makes people more accepting of risks and accidents by reducing the negative consequences of bad judgment. Trying to find the psychological component of suggested laws often leads to different conclusions over what previous assumptions (and even common sense) would dictate.

So please, enough with those annoying “buckle up” commercials on TV.