02 June 2010

Stat Attacks - Numbers as Weapons in Discouraging Cycling

There was a recent, symbolic raid on bicycles last week where the police went after our cycling citizens for fun and profit.

There was coverage on every news channel about the police handing out fines and in every broadcast and in every newspaper article one number was mentioned. 20,000 cyclists are admitted to hospital every year in Denmark. It had absolutely no context for the bike raid, but it was repeated again and again.

I was thinking about the affect heuristic in relation to how we should be promoting cycling. Wikipedia has a page about the affect heuristic but Eliezer Yudkowsky has a great article about it on the excellent Less Wrong blog - a 'community blog devoted to refining the art of human rationality'.

As Yudkowsky puts it, "The affect heuristic is when subjective impressions of goodness/badness act as a heuristic - a source of fast, perceptual judgments. Pleasant and unpleasant feelings are central to human reasoning..." A paper I'm looking forward to getting my fingers on is The affect heuristic in judgments of risks and benefits. Journal of Behavioral Decision Making by Finucane, M. L., Alhakami, A., Slovic, P., Johnson, S. M. (2000)

The affect heuristic is in play more than ever in modern society, thanks to the regrettable development of The Culture of Fear. Not least here in Denmark.

The "20,000 cyclists admitted to hospital" isn't a number that a dozen journalists googled by coincedence. It's a number sent out in a press release so that journalists don't have to think for themselves. Not surprisingly, it's the Danish Road 'Safety' Council who controls the distribution of such statistics. They really should open a car dealership on the side.

Stats like that one have incredibly negative effects on risk perception. Over the past two years, the flow of negative stats has increased. The main problem is that if you have a leak of negativity, you should also have a plug. We need a plug here in Denmark. We need a counterweight to the car-centric flow of information. We need people to fight for cycling, because we're killing it off. That's what bicycle advocacy is all about.

Looking around the world at colleagues I've met there are many who work hard at plugging. Fietsersbond, the CTC in the UK and FUBICY in France spring to mind. Countering the negative press and destructive stats that filter out of other organisations. Cyclists up in the UK! Um, yes... but cycling is up so actually the number of accidents is down. Safety in numbers principle. Duh...

If you keep repeating something like "20,000 cyclists end up in the hospital every year", it starts to sink in that cycling is 'dangerous'. This is the affect heuristic at play in all the wrong ways.

In the press we never hear details about these emergency room visits. Many, if not most, are minor injuries to arms and legs. We don't hear whether or not most cyclists walk out of the emergency ward and ride home, which is quite likely. I recall a stat from Norway about how 90% of cyclists who visited a hospital were on their bike again within the week. An important detail to include, don't you think? Provides a rational balance to the shockhorror angle.

I was at the hospital last week, actually. Just for some tests. Got talking to the doctor who told me that she commutes by train from Odense - an hour and a half away from Copenhagen. I asked, innocently enough, if she had a bike parked at the Nørreport train station - which is a 10 minute ride from the national hospital.

No, no... she 'didn't dare cycle in Copenhagen'. I assured her that we live in one of the world's two safest countries to cycle in. She was interested to hear that but she's been affected - affect heuristic again - by the negative press cycling has had over the past two years.

The City's Bicycle Office knows that scaring people off of bikes doesn't do anyone any good. In an interview with a Toronto newspaper, Andreas Rohl, project manager for Copenhagen's cycling infrastructure, said "We try to never talk to the public about cycling safety. [...] We just feel if we start to talk publicly about safety, people will start to doubt if cycling is safe..."
How Not to Promote Cycling
This is apparently how the Road Safety Council 'sells cycling' in Denmark

Let's look at numbers. Danes cycle 30% less than they did in 1990. According to the brilliant research by Prof. Lars Bo Andersen at the University of Southern Denmark, if will still cycled those 30% we could save 1500 lives a year through the health benefits of cycling. We both spoke at a conference last year, actually, and I asked him about it. He said that the 1500 number is low. Way too low. I'm looking forward to seeing what number he comes up with.

Shouldn't this positive news about the health benefits of urban cycling be repeated constantly? Shouldn't stats like this be one of the plugs to stem the flow of car-centric information?

Let's look at the 20,000 number with layman's eyes.

According to the national statistics, 18% of Danes cycle each day.
There are 5,540,241 people in Denmark, according to the latest numbers from last month.

That means there are 997,243 people commuting to work or school each day. Let's be realistic but, at the same time, conservative. Let's make that number 1.3 million to include short trips by bike that never get counted in commuting stats. It's probably much higher.

So... 1,300,000 people use a bicycle each day.
20,000 are admitted to hospital for minor or major injuries.
That means that only 1.5% - probably lower - of our daily cyclists are unlucky enough to need medical assistance.

On the other hand, those 1.3 million people ride every day.
1.3 million people times 365 days = 47,450,000
20,000 hospital admittances is 0.042%.
Goodness... that looks good.

Which headline is most positive and likely to encourage people to cycle?

20,000 cyclists hospitalised each year!


Only 1.5% [or 0.042% if you like] of cyclists hospitalised each year! Most of them for minor injuries!

Traffic deaths are always tragic. No doubt about it. In Denmark every around 45-50 cyclists are killed in traffic accidents. Like everywhere else, the majority die in accidents with cars. Which is why we shouldn't ignore the bull.

Let's say 50 cyclists lose their lives each year.
Out of the same 1.3 million Danes.
That's 0.00384%.

Let's balance that with the fact that, according to the comprehensive research by Prof. Lars Bo Andersen, cyclists live seven years longer, are less ill whilst alive and enjoy a higher quality of life.

And I recall reading that BECAUSE we cycle so much we save 600 lives a year! That's AMAZING news! Where are the headlines?

"Cycling is safe!"
"Safety in numbers... get on your bike and make cycling safer!"
"600 lives saved every year by cycling!"
"Save your life! Ride a bike!"

Etcetera. Ad libitum.

There is much talk of risk per kilometre [or mile] travelled. This is probably the most car-centric twist on traffic statistics in history. I heard a year or so ago that this way to angle the stats was an invention of the car industry, but I've never been able to find out where it originated or when it was first brought into use. Which all makes it feel a bit like the mystery surrounding the invention of Cap-and-Trade C02 trading schemes by Enron and Goldman Sachs and Al Gore.

If risk per kilometre was worth anything, space travel would be the safest form of travel. However, after a quick google, I learned that 32 astro/cosmonauts have lost their lives, out of 517 people who have travelled in space. Not great odds. I'll stick to my bicycle. It takes me to the moon and back every day.

The whole point is that those of us who wish to promote cycling should focus most intensely on countering the attempts by others to brand cycling as dangerous. Including those who provide negative affect heuristic statistics.

It's promoting cycling, it's basic marketing.

We're not doing it good enough. It's madness.


Anonymous said...

It's a little disturbing to read between your lines and see that all is not well in the Copenhagen cycling world. Over here in Australia we're used to imagining that Copenhagen is a cycling nirvana; that's what the word "Copenhagen" means to us.

I see stat wars being played out on this issue on various bike forums. The main one is regarding mandatory helmet laws (which we are unfortunate enough to have here), but there is another never-ending one on whether cycling is safe/dangerous.

A few people get converted by these stat wars, but most are not numerate enough to get anything out of them. Pictures of attractive, unhelmeted people on bikes seems to work better as advocacy :)

Kevin Love said...

Here in Toronto, the City's Medical Officer of Health, Dr. David McKeown, came up with a report on people killed and injured by car pollution. He reports that 440 people in Toronto every year are killed by car pollution, and 1,700 are injured so seriously by car pollution that they have to be hospitalised.

The report may be found here:

I use this as my affect heuristic in talking about car driving. I say things like "every time someone turns on a car engine, they are participating in killing 440 people in Toronto."

I am repeating this over and over again. The goal is to get car drivers to remember this fact every time they turn the key in their car's ignition.

l' homme au velo said...

We have this same attitude in Ireland by the News Media for many Years. They never feature anything about Cycling it is all about Traffic Flow and Congestion and what is the best Cars etc.
The only time Cycling was mentioned was for Negative reasons to say how unsafe it was particulary if there was a Cyclist fatality. The truth of it is there is very few Cycling fatalities but loads of fatalities involving Cars.

The situation was terrible 20 Years ago for Fatal Car Accidents but with a tightening up of Regulations this has all been going down. But still we have something like 400 Fatalities every Year in Ireland mostly involving Cars. A lot of these are single Car Accidents in the early Hours with Cars Crashing into Ditches and Walls in Country Areas and Motorbike Accidents and some Pedestrians being knocked down but only one or two Cyclists being Killed each Year.

The two recent Fatal Accidents involved Trucks Turning Corners and catching Cyclists on the inside this was earlier in the Year. No surprise there ,although this is rare now in Dublin it is happening a terrible lot on the Roads of London in the UK.

Recent Years Cycling has become Tremendousely Popular in Ireland with more getting out on their Bikes each Year,but we still have this Negative attitude of the Media who are very Pro Motorist.

However things are looking up for the better with a gradual shift in their Ideas and a grudging recognition of the fact that Cycling is Cool and Hip. The Promotion of Cycling by the Government and Bike Week and now lately Cyclic Chic has even Spurned them on to write some articles in glowing terms about Cycling.There was a very nice Photo of A Cycle Chic Promoting bikeweek.ie yesterday in the Irish Independent.

So things are looking up for Cycling in Ireland in spite of the Negative Reactions from mostly the Car Lobby.

Mikael said...

Anon: we are some people doing what we can to promote cycling positively. amazingly, there are people in this country doing the opposite. it's universal, i suppose.

kevin: Similar study here from Denmark about how Traffic (pollution) kills ten times more people than traffic accidents

unfortunately, you hear a lot of Ignoring the Bull here.

l'homme... i'm SO looking forward to coming to Dublin for the Cycle Chic event!

Anonymous said...

l' homme au velo, there are about a dozen cyclists killed in Ireland in a typical year, not one or two.


It's still comparable to accident statistics for other modes of transport, and you're quite right: the Irish media do portray cycling as dangerous when it is not. At least not if you regard being a pedestrian as dangerous, since that has similar injury statistics.

Brent said...

One view on the origin of the mileage death rate (MDR) metric:


"But experts through the years have searched for a better way of measuring the accident problem, and all of the experts, including people from the Federal Establishment, have not been able to find a better method."

Another older, but good article discussing various metrics:


"The safety of walking and bicycles depends almost entirely on the other transportation with which they must mix."

Kenneth said...

How about a Kills Per Mile statistic, counting how many deaths per mile travelled a form of transport is responsible for. This number says something about the impact on society a certain form of transport has. (Not sure precisely what, but it says something :-)

I guess cycling would be close to 0, walking maybe even 0, while driving would be a bit higher. I guess that out of the 3-400 traffic deaths each year in Denmark, only a handful of them are not caused by cars or lorries.

Jonathan Krall said...

Thanks for taking on the "risk per kilometer" nonsense. The point of a transportation system is not to maximize distance traveled, but instead to get people where they want to go, quickly and safely. In my opinion, the best measure is "risk per trip."

For example, last June my bicycle commute became shorter when the traffic network added connectivity (a new bicycle-accessible river crossing). My bicycle commute became shorter in distance and quicker in time. Therefore I am exposed to less danger each day while still getting to and from my job. A "risk per mile" metric won't show me to be safer. A "risk per hour" metric doesn't work either. The "risk per trip" metric works.

The "risk per trip" metric shows that a better-connected network is safer. It also shows that any public policy that discourages long trips generally increases safety.

sexify said...

Speaking of which, did you know that "There is no evidence that the helmet law discourages cycling or harms the health of New Zealanders - there is evidence that it has contributed to a reduction in cyclist head injuries"? That's from a NZ 'safety authority spokesman'.



ThorbjørnK said...

I'd like some stats on bike accidents vs car accidents, how many people are injured in cars per year or per kilometer?

I have had 2 friends of mine die in separate car accidents, and two others hurt, one with the driver getting severe brain damage, but I've not even heard about a single of my friends getting hurt above "I tripped on my bike and hurt my shoulder".

I've fallen off my bike multiple times and never hurt myself so much as to not get back on within 5 minutes.

Anonymous said...

Anti-cycling propaganda from jackass Jim Kenzie, the Wheels section editor of the Toronto Star:


Jeff said...

I wonder how many automobile drivers are admitted to the emergency room every year... maybe if put into context, cycling wouldn't be much more dangerous the driving?

Administrator said...

A thought provoking blog that makes me think my blog is anti-cycling!

10 minutes in my blog and there is no way you would cycle in Adelaide Australia.

Marco te Brömmelstroet said...

Here you have the article you wanted to have your fingers on: http://www-abc.mpib-berlin.mpg.de/users/r20/finucane00_the_affect_heuristic.pdf