Slides from my lecture on the public perception of risk

Powerpoint presentation delivered at Imperial College on October 14th 2013.


Tom Vernon: Fat Man on a Bicycle

My old friend Tom Vernon has died aged 74. I was honoured to be asked by his wife Sally to write his obituary for the Guardian. Here it is – http://www.theguardian.com/media/2013/sep/18/tom-vernon


Pater knows best?

Risk compensation – the proposition that a person’s perception of risk influences their risk-taking behaviour – has now become conventional wisdom.  No one now disputes that rock climbers with ropes will attempt manoeuvres that they would not attempt without them, or that trapeze artists will attempt manoeuvres with nets that they would not attempt without. The insurance industry calls it “moral hazard” and accepts that people with insurance take more risks than those without.  Financial regulators now acknowledge that banks that believe themselves, and their trading partners, to be too big to fail will take risks that others would not – confident of their government safety net.

Risk compensation has become conventional wisdom with a peculiar blind spot  – seat belt laws. Seat belts have become the popular metaphor for just about anything that offers protection against just about anything. Googling “fasten your seat belts” yields half a million hits – almost none of which has anything to do with road safety: the top hit at the time of writing this is “Fasten your seat belts – a balance of payments crisis looms”.

Repetition has created a constantly self-reinforcing myth that has rendered belief in the efficacy of seat belt laws impervious to attack. A new book entitled Against Autonomy: justifying coercive paternalism has just been called to my attention.  Its cover announces seat belts as its iconic exemplar of effective “coercive paternalism”. Conly deploys the “success” of seatbelt laws as a justification for further applications of coercive paternalism such as banning smoking:

“… we see widespread acceptance of seat belt laws, even for adults who are sober, rational, competent, and so on, because they so clearly prevent great harms in circumstances where there is no other way to stave off the damage that will otherwise ensue. “ (p5)

 Screen Shot 2013-06-10 at 12.07.34

 No need to cite evidence. Their prevention of great harm is so clear and obvious.

Such routinely reiterated publicity for the life-saving effect of seat belt laws helps to explain why they don’t save lives. The risk compensation effect works through perception. If you perceive that something will make you safer you will modify your behavior. Both the belt itself, and the incessant publicity for hugely exaggerated claims for its effectiveness, help to account for the fact, now acknowledged even by supporters of the law amongst the leadership of Britain’s Parliamentary Advisory Council for Transport Safety, (see “Seat belt laws: why we should keep them”), that Britain’s seat belt law led to an increase in the numbers of pedestrians and cyclists killed.

The law didn’t work precisely because coercive paternalism was overridden by autonomous drivers. Pater could compel them to belt up, but could not compel them to want to be safer than they chose to be.

A thoughtful review of Against Autonomy by the person who brought it to my attention can be found here – http://grumpyarthistorian.blogspot.co.uk/2013/06/sarah-conlys-against-autonomy-reviewed.html .

Readers new to this argument can catch up here – http://www.john-adams.co.uk/category/seat-belts/


Change has to take root in people’s minds

The main headline in today’s Daily Mail reads:

£90 fine if you’re texting at the wheel: Minister warns of safety crackdown

US experience suggests that the crackdown is unlikely to achieve its desired effect. There the success of attempts to deal with the texting-while-driving problem by means of legislation has been the subject of a number of natural experiments. In the US such laws are a matter of state jurisdiction and some states have passed laws while others have not. This has permitted before-law and after-law  comparisons of states that passed laws with adjacent states that did not.

The results were interesting. A study by the Highway Loss Data Institute in 2009 found that banning texting while driving had a perverse effect – crashes increased. The HLDI explanation for the this result was that after the ban texters texted with their phones in their laps – where they were less visible to the police –  rather than on the steering wheel as before, with the result that they were even more distracted from the driving task. Here is the result for California.

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California – Collision claims per 100 insured vehicle years, by month before and after law for all drivers, compared with Arizona, Nevada, and Oregon.

As philosopher Michael Sandel has observed, “Change has to take root in people’s minds before it can be legislated.” Nowhere is this more obvious than on the road. Countries in the early stages of motorisation have death rates per vehicle many times higher than those of highly motorised countries. And yet most of them have on their statute books the full panoply of imported road safety legislation – from seat belt laws and speed limits to bans on drinking and driving. These laws are simply not enforced, not obeyed, or both.


The ever receding yet

Historian Niall Ferguson has been reported as apologising for “remarks in which he implied that John Maynard Keynes did not care about future generations – because he was childless and gay” – leaving open the cause of Keynes’ indifference to the long run. This provoked a letter from me to today’s Guardian. For non-Guardian readers here it is.

Niall Ferguson apologises

 How embarrassing. Forget the homophobia. The renowned historian appears to be unaware of Keynes’s famous grandchildren (Report, 4 May). In an essay written in 1930, entitled Economic Possibilities for our Grandchildren, Keynes marvels at the power of compound interest, and invites the reader to join him in pondering the impossibility of it compounding forever. He imagines the advent of “an age of leisure and abundance” in which his (hypothetical) grandchildren – now well into retirement – will be set free “to return to some of the most sure and certain principles of religion and traditional virtue, that avarice is a vice, that the exaction of usury is a misdemeanour, and the love of money is detestable”. But, writing at the beginning of the Great Depression, Keynes warns: “Beware! The time for this is not yet.”

What unites today’s economists, Keynesian or not, is the conviction that we are still a long way from “yet”. The central challenge being addressed by governments everywhere is how to get economic growth restarted, and then growing faster – without apparent end. If not yet, when?


The Boston Marathon Bombs

In the aftermath of the 2005 7th July bombings in London I wrote a piece entitled “7/7: What kills you matters – not numbers

I illustrated it with a diagram highlighting the remarkable lack of correlation between quantified measures of risk and common response. I identified two key variables that helped to explain this lack of correlation: the level of control that those taking, or exposed to, the risk felt that they had and, in the case of involuntary risks, the perceived motives of the imposer of the risk.

Risk Amplification

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52 people were killed by the 7/7 bombers. I noted that in Britain at that time “on an average day nine people die and over 800 are injured in road accidents. The mangled metal, the pain of the victims, and the grief of families and friends, one might suppose, are similar in both cases. Measured in terms of life and limb, 7/7 represented six days of death on the road. But thousands do not gather weekly in Trafalgar Square to manifest their collective concern.”  Why?

Simon Jenkins has become a routinely calming and rational voice in the aftermath of such events. Discussing the Boston marathon bombs he provides a good answer in today’s Guardian. He succinctly describes the problem: “Such deeds are senseless murders. … What makes them terrorist is the outside world rushing to hand their perpetrators a megaphone.” See “After the bomb, hysteria is the terrorist’s best weapon”. I recommend it.

Another recommendation from yesterday’s New York Times by Thomas Friedman: Bring On the Next Marathon.


Now wash your hands

I recently visited an exhibition at the Barbican Centre in London entitled “The Bride and the Bachelors: Duchamp with Cage, Cunningham, Rauschenberg and Johns

More recently I was invited to speak to a conference entitled “Risk culture for charities” organised by the Institute for Risk Management.

I began my conference presentation with an overview of disparate risk-management cultures, offering examples of excessive risk aversion in the form of fatuous warnings of manifestly obvious directly perceptible risk. And I concluded with a cartoon that I felt made the point rather well.

brick wall

                                                                                         Guindon, Detroit Free Press, 25 September 1994

As the profusion of signs warning of obvious and/or trivial risks grows, I suggested, the likelihood increases that warnings of serious/non-obvious risks will be ignored.

After my presentation, and after tea, one of the conference participants returned to report that every urinal in the men’s toilets displayed the injunction “Now wash your hands”.*

The centrepiece of the Barbican’s Duchamp exhibition was his famous urinal – signed “R. Mutt 1917”.  I have long had trouble with Duchamp’s success in transforming it into “a work of art”.  But work of art, or no, it clearly needs updating to keep up with modern risk management practice.

duchamp hse

* He also reported that the man next to him departed without washing his hands.






Last Thursday (21 March 2013) I attended a conference entitled “Lies, Damned Lies and Statistics? Understanding casualty trends and the causes”. It was sponsored by the Parliamentary Advisory Council for Transport Safety (PACTS). At the conference PACTS, the Department for Transport, and seven other organizations interested in promoting road safety launched a website called www.roadsafetyobservatory.com.

Its home page promises:

Key facts and summaries of research on road safety topics

The website proclaims:

“The Road Safety Observatory aims to provide easy access to independent road safety research and information for anyone working in road safety and for members of the public. It provides summaries and reviews of research on a wide range of road safety issues, along with links to original road safety research reports.”

Its objective, the person presenting it made clear, was to provide an authoritatively fact-checked set of statistics to inform public discussion of road safety issues. Under the heading “How is the Research Evidence Produced?” it states:

“The Programme Board commissions Research Reviews from a wide range of researchers and road safety experts. Each Review is then submitted to an independent Evidence Review Panel, who must approve it for publication on the Observatory website. The reviews are intended to be free from bias and independent of Government policies and the policies of the individual organisations on the Programme Board. They represent a summary of the best evidence readily available to the research community and will be kept under review as new evidence emerges.”

I decided to subject this new source of evidence to my standard test. Into the Home Page search bar I typed “seat belts” – do try it at home. This took me to “Road Safety Observatory Seat Belts Review, January 2013” – bang up to date and approved by the Independent Evidence Review Panel. First up came “SEAT BELTS: KEY FACTS”.

Seven bullet points down I found this “Key Fact”: “By January 2008, 25 years after the introduction of the law, front seat belts had saved over 60,000 lives in Great Britain.”

On page 5 the claim is embellished: “By January 2008, 25 years after the introduction of the law requiring car drivers and front seat passengers to wear seat belts (if fitted), it was estimated that front seat belts had saved over 60,000 lives in Great Britain.”

On page 9 the claim is repeated – twice.

And again on page 32: “Seat belt laws increase seat belt use, and so reduce death and injury. 25 years after the first law requiring seat be to be used, it was estimated that front seat belts had saved over 60,000 lives in Great Britain.”

The claim that the seat belt law saved 60,000 lives over 25 years is reiterated five times in a document approved by the Observatory’s Independent Evidence Review Panel – without any supporting citation I could find.

Citations are no longer needed. The claim has been repeated so often that it has become a “fact” that everyone knows. Typing “seat belts 60,000 lives saved” into Google yielded, at last clicking, over one million hits.

THE CLAIM IS OUTRAGEOUS NONSENSE.  According to this claim the seat belt law is, by far, the most effective road safety measure ever implemented in Britain. 60,000 divided by 25 years would equal 2400 lives saved every year since 1983 by the seat belt law.  In 1982, the year before the seat belt law came into effect there were only 2365 driver and front seat passenger fatalities! The claim is further, if less dramatically, contradicted by other claims in the same review – indeed in the same initial bullet point: “It was estimated that the seat belt law saved the lives of 241 drivers and 147 front passengers in 1983 and 270 drivers and 181 front passengers in 1984.”   The review does not provide a citation for the estimate of lives saved in 1983 and 1984 but they are similar to those provided in a June 2008 article in Significance by Richard Allsop, Oliver Carsten, Andrew Evans, and Robert Gifford (all members of PACTS). See table below.

Significantly the Significance article did not make it into the Review’s list of key references on seat belts. A significant omission because the authors, all defenders of the seat belt law, acknowledge an effect of the law of important consequence to vulnerable road users. They say “the clear reduction in death and injury to car occupants is appreciably offset by extra deaths among pedestrians and cyclists.”


This surely deserves a place in any list of “Key Facts” relating to the seat belt law.

Another Key Fact that did not make it into the review is the finding that almost all of the 1983 decrease in driver fatalities estimated by the authors of the Significance article took place between 10pm and 4am (the “drink drive hours”) and in drivers with alcohol in their blood. During the other hours of the day, and amongst alcohol-free drivers there was no detectable departure from trend (see Risk chapter 7). 1983 also happened to be the year in which evidential breath testing was introduced, and unprecedented numbers of breath tests were administered, and drink-drivers prosecuted. The modest claims (modest when compared to 2400) for lives saved in the table above can only be attributed to the seat belt law if one assumes that the measures introduced by the campaign against drink driving launched in the same year had no effect.

Who cares? Why does all this matter 30 years after the seat belt law came into effect? It matters because a new website sponsored by what might be called Britain’s road safety establishment, and promising unvarnished, unbiased, objective “Key Facts”, is telling a whopper. And not out of ignorance. The last time I looked PACTS, RoSPA and the DfT, key sponsors of the new website, all had the 60,000 claim still on their websites despite its absurdity having been called to their attention on a number of occasions.

The PACTS conference was well attended by people with a common interest in making roads safer. There was a detectable, and welcome, shift in emphasis from previous conferences I have attended from a focus on legal and engineering approaches to the problem, to an interest in changing attitudes and behaviour. As I have noted in   Managing transport risks: what works?  :

 “There are two different kinds of manager involved in the management of transport risks: there are the “official”, institutional, risk managers who strive incessantly to make the systems for which they are responsible safer, and there are the billions of individual fallible human users of the systems, each balancing the rewards of risk against the potential accident risks associated with their behaviour.”

 Understanding the attitudes of the latter to risk, and influencing their consequent behavior, represents the most important and challenging part of the institutional risk manager’s job.

 Seat belts have acquired iconic status in common parlance. “Fasten your seat belts” is a phrase commonly invoked to introduce any exciting or threatening idea into a discussion. It is routinely used as a comparator for the postulated benefits of other forms of safety legislation such as cycle helmets. It reinforces legislator hubris – “look what we have achieved!” they marvel as they pat themselves on the back. The Road Safety Observatory by virtue of its endorsement of the 60,000-lives-saved claim is further entrenching the iconic status of the seat belt law and energizing legislators keen to pass further well-meaning but misguided legislation.

 To undo this damage PACTS, RoSPA and the DfT need not just quietly remove the claim from their websites, but prominently explain why.  Likely to happen? Don’t think so.

 Recent posts and comments on this subject are on my website at http://www.john-adams.co.uk/category/seat-belts/



Repeal the Seat Belt Law

Peter Bonisch  has posted a comment on my RoSPA post (11 February) that merits an answer. He asks: “would you advocate now removing the seatbelt requirement?  The world has changed since the law was introduced including having been changed by it.  Would it now be constructive to abolish the law in the knowledge that we would not simply revert to the ex ante position?”

Good questions.

I would not expect to return to the ex ante position. And yes, I would repeal the law.

Over the last 30 years road accident deaths in Great Britain have fallen from 5934 to under 2000, but the clear downward trend is not a demonstrable consequence of any government “safety” interventions over that time – see Managing transport risks: what works, Figures 1, 2 and 3.

The long-term trend in the ratio of pedestrian and cyclist fatalities to car occupant fatalities has also displayed a downward trend as car traffic has increased and the number of vulnerable road users (cyclists and pedestrians) on the road has decreased – with a significant interruption to the trend in the year that that the seat belt law was implemented – see p. 10 of what works. An important contributor to this trend has been the enormous drop in the number of children allowed on the streets on foot or on bicycle without adult supervision – see Children’s independent mobility: a comparative study in England and Germany (1971-2010) 

Bonisch notes that there have been technological advances in safety over the past 30 years, such as airbags, improved braking and anti-collision technology. But these changes appear to account for very little, if any, of the decline in road death rates with increasing levels of motorisation. Today motorists in poor countries in the early stages of motorisation are achieving kill rates per vehicle – driving  vehicles with one hundred years of safety technology built into them – as high or higher than were achieved by Model-Ts in the early 19th century. The probable reasons for this are explored in Where and when is shared space safe? 

Bonisch contends that the world has been changed by the seat belt law, and I agree. It has shifted the burden of risk on the road unfairly from the best protected in cars to the most vulnerable outside cars.

Finally, I rest my case on John Stuart Mill’s famous dictum opposing measures that would compel people to be safer than they voluntarily choose to be: “all errors which he is likely to commit against advice and warning, are far outweighed by the evil of allowing others to constrain him to what they deem his good”.

I would repeal the law.



Open letter to Tom Mullarkey, CEO of the Royal Society for the Prevention of Accidents.

Dear Tom

Following our meeting at a dinner at the RSA over six years ago I sent you an email (22 February 2007).You replied the same day saying “When I have a moment, I would like to look into this in more detail and so I will follow up on the links you have kindly provided.”

I guess you’ve been busy.

In any event RoSPA’s press release on 31 January 2013 celebrating the 30th anniversary of the seat belt law, and RoSPA’s contribution to it, have given me an excuse to revisit the issue.

At dinner I had told you about RoSPA’s dubious lobbying practices in the run-up to the Parliamentary debate in 1981 and promised to send you some chapter and verse. In my 22 February email I noted that I had already detailed some of this dubious practice in my book Risk and Freedom (p152). I quoted from my book:

“On July 7 1981 The Royal Society for the Prevention of Accidents (president – Lord Nugent) sent a letter to every member of Parliament stating

‘Dr. Adams has recently published a paper advancing the thesis that the wearing of seatbelts may actually increase road accidents by encouraging a false sense of security. His paper [subsequently peer-reviewed and published unaltered by the American Society of Automotive Engineers]  presents road accident trends in several foreign countries to support his view. His paper requires detailed analysis with the aid of much background information from the countries concerned before an authoritative comment can be made upon it. RoSPA and the Transport and Road Research Laboratory are undertaking these studies, meantime it is relevant to record that Dr. Adams does unequivocally state that wearing seatbelts greatly improves the chance of avoiding injury.’ “

This last sentence, I noted, unequivocally misrepresented my position. As I said at dinner, the statistics demonstrate that a seat belt improves your chance of surviving a crash, but INCREASES your chances of being in one. I went on to say

“This letter throws a revealing light on the campaigning methods of RoSPA at the time. While publicly stating that much more work needed doing before they could comment authoritatively on my findings, privately they had been briefing selected members of Parliament for three months with a document which asserted confidently that my conclusions were ‘absurd’ and ‘without foundation’ and that I ‘exhibited, at best, a layman’s understanding of the situation.”

I wrote to you next on 30 September 2009 and again on17 October 2009 inviting your comments on my online contention that RoSPA, in celebrating the 25th anniversary of the seat belt law, was making ludicrous claims for its effect.

Having failed to elicit any response four years ago now, on the 30th anniversary, I renew my invitation in the form of an open letter. I invite your comments on my recent post “30 years in the jungle with RoSPA” .

I invite two comments in particular:

  1. Given that on the third anniversary of the law Lord Nugent, your former president, was claiming that the law was saving 200 lives a year, how do you justify RoSPA’s recent anniversary claims of 2400 lives a year – i.e. 60,000 lives saved over 25 years?  (Please note my answer at the time to the evidence on which Lord Nugent relied for his claim of 200 lives saved –     Journal of the Royal Statistical Society Series A, 149, 187-227.)
  2. In the light of the comment by Lord Nugent that RoSPA “certainly could not support any road safety measure which discriminated in favour of one section of the community rather than another” – do you think that my “Organ Harvester Lottery” is a fair characterization of the discrimination acknowledged by Allsop et al in their Significance article?

Hoping to hear from you


PS  This open letter is not an attempt to settle very old scores. It is an attempt to get RoSPA, an influential organization concerned with risk management, to confront the reality of risk compensation.

When I first became involved in the seat belt debate over 30 years ago the risk compensation hypothesis was jeered at in Parliament: it was “bogus”,  “spurious”, “eccentric”, “ludicrous” and, more politely, “unproven” and “new”. It now merits a Wikipedia entry:

Risk compensation (also Peltzman effect, risk homeostasis) is an observed effect in ethology whereby people tend to adjust their behavior in response to perceived level of risk, behaving less cautiously where they feel more protected and more cautiously where they feel a higher level of risk. The theory emerged out of road safety research after it was observed that many interventions failed to achieve the expected level of benefits but has since found application in many other fields.

That people adjust their behavior in response to changes in perceived levels of risk has now become a commonplace. Where (if) there is debate about the phenomenon it now usually focuses on whether compensation is partial, complete, or more than complete – except in the case of seat belts legislation where, for campaigners such as RoSPA, it apparently still does not exist.

Acknowledgement of the phenomenon is essential to an intelligent civilized discussion of any risk management problem. A quick Google search will show that it features in discussions ranging from flood control, anti-lock brakes, cycle helmets, sexual behavior, skydiving, and sub-prime mortgages to shared space and warship safety – amongst many others.

RoSPA’s continuing repetition of its nonsense claims for the efficacy of Britain’s seat belt law is in danger of undermining its credibility in other areas where it undertakes useful work.

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