Brian Nosek and his shades of grey

January 31, 2016

In this blog I have featured many psychological experiments, Stanley Milgram persuaded ordinary people to administer what they thought were 450-volt electric shocks to subjects in an educational experiment. Philip Zimbardo famously had 25 Stanford students play the roles of guards and prisoners in a two-week experiment that had to be suspended in under a week. And David Rosenhan managed to get eight sane people, including himself, admitted to various psychiatric hospitals in the USA, by briefly simulating auditory hallucinations.  What proved more difficult was to get them out. All these experiments have achieved iconic status in psychology.

Here is one experiment I haven’t featured before. A study observed that political moderates were better at perceiving shades of grey accurately than left-wing or right-wing extremists. It is an amazing result, and yet it does seem to have a ring of truth about it. The researchers could, perhaps should, have stopped there. They could have sent it in a renowned psychological journal, because this result was eminently publishable. However, they decided to run the test again with a very large sample. Alas, the result didn’t show the second time. Now there hopes of publishing a paper had gone up in smoke. They couldn’t send both studies to a journal – it just wouldn’t be published. Had they just sent the first one, it would have been far more likely to have been accepted.

So, how reliable are psychological experiments? Scientific claims are not based on someone in authority saying that it is true. Reputation is not decisive. What is important is that the findings can be independently reproduced; another scientist following the same procedure will achieve the same results.

Enter Brian Nosek a psychology professor from the University of Virginia, the man behind the study about the shades of grey. Nosek, a social psychologist and the co-founder and director of the Center for Open Science, was able to persuade 270 of his peers to take part in a study repeating 100 published psychological experiments that had been published in prestigious psychology journals in 2008 to see if they could get the same results a second time around. The Reproducibility Project, which began in 2011, was supposed to take between six and nine months. In reality it would last three years. The project was a curious enterprise. There were no eureka moments. This was not cutting-edge research that would lead to fame and glory. Nevertheless, it is vital that it be carried out.

The results were finally published in the prestigious Science magazine last summer. 97% of the 100 studies originally reported statistically significant results. This is what you’d expect. Many experiments fail to produce meaningful results, and they are not generally published. This is what is known as publication bias. It is also sometimes known as the “file drawer effect” – results that do not support their hypotheses will stay in the researchers’ file drawers. In the new study just 36% of the replications reached statistical significance. This needs to be analysed; just because something fails to replicate doesn’t mean it isn’t true. Some of these failures could be down to luck, or poor execution, or an inability to reproduce the conditions needed to show the effect. Nevertheless the results were not good.

What is going on is probably not fraud. The problems are more subtle than that. We must stop treating single studies as unassailable versions of the truth. There is a pressure to publish. It is novel findings that are sought, and there is little incentive for attempts at replicating findings, such as those carried out in the Reproducibility Project.  I also think that many of the studies should be true. There is something seductive about them. I remember reading one experiment that showed that if you hear that if you are holding something warm, such as a cup of coffee, you are more likely to perceive someone else as emotionally “warm”, and you are more likely to behave in a friendly, generous way. This may well be true but I would like to know whether or not it has been replicated.

And I fear that this lack of reproducibility is confined to psychology. Another study found that around $28 billion worth of research per year in medical fields is non-reproducible. Discoveries should be thoroughly examined and repeatedly observed before they are universally accepted. Published and true are not synonyms. Scepticism is what makes science so powerful.  We are now seeing reforms and they need to continue. There should be more transparent reporting, a clear hypothesis before any data is analysed, and sharing of the results so that they may be vetted.  I look forward to more work from the Center for Open Science in the future. There may not be much glory in it, but the researchers who do it, will be making the world a better place

When social interventions go wrong

November 15, 2015

The other day I was listening to the Start the Week podcast, when I heard them talking about an Oscar-winning documentary I remembered seeing in the late 1970s. In one chapter of his new book, Black Box Thinking: The Surprising Truth About Success Matthew Syed analyses Scared Straight, a 1978 documentary which showed a group of seventeen troubled teenagers with convictions for shoplifting, theft, assault possession and selling of drugs, to Rahway Penitentiary in New Jersey. There they would meet convicts who had been sentenced to at least 25 years for crimes such as homicide, rape, armed robbery, and drug dealing. The crime-reduction programme “Scared Straight”, which had been an idea of the prisoners themselves, had already been running for two years when the documentary was made. The idea was to shock the kids into giving up their criminal ways by giving them a glimpse of what life was really like inside a maximum security prison.

I remember being impressed by the programme. Directed by Arnold Shapiro and narrated by Peter Falk, the documentary was broadcast uncensored, which was rather surprising. We were just not used to hearing the f-word on TV. The mores of the 1970s were very different from now. There was no Channel 4 in the UK, and I’d never heard of HBO, although it had actually been founded in 1972.

Initially, the teens come across as cocky – they are not going to let themselves be intimidated. But the meeting is designed to intimidate them. Walking through the metal detector at the entrance of the prison, the youngsters experience their first taste of harsh prison life. As well as a lot of swearing, the kids hear tales of murder and rape. There are a number of kids who were picked on by the prisoners. The kids are inside Rahway for just three hours, but it feels much longer. They have seen the reality of prison and are determined never to go back.

In 1979 Scared Straight won the Oscar for best documentary feature at the Academy Awards. There was then a celebratory 20th anniversary programme – Scared Straight! 20 Years Later, fronted by Danny Glover. It revisited the 17 subjects from the original film. As they talked about their new lives, almost all said that the 3-hour visit to Rahway two decades earlier as having turned their lives around. A&E, an American cable and satellite channel, introduced Beyond Scared Straight, a new series, in 2011. It ran for eight seasons.

Here is a government program which actually works. For a relatively small outlay it is possible to get a significant reduction in crime. The “Scared Straight” programme was rolled out to a number of other states. Indeed it was even adopted abroad – Canada, the UK, Australia, and Norway have all tried it out. According to the evidence of those who ran these crime production programmes, between 80% and 90% of people who attended the program went straight. If this were true, we would be looking at an unprecedented success.

Enter James Finckenauer, a professor at the Rutgers School of Criminal Justice, who decided to test Scared Straight. Was the evidence supporting these programmes solid? Digging a little deeper, Finckenauer discovered that it was based on a questionnaire sent to the parents or guardians of children who had visited Rahway. There were four yes-or-no questions:

  1. Have you noticed a marked change in your child’s conduct since their visit to the prison?
  2. Has there been a slight change in their behaviour since their visit to prison?
  3. Do you think another visit is necessary for your son/daughter?
  4. Are there any specific areas you think we might be of some assistance to you, or your son or daughter?

What you may notice is that these questions are rather subjective. What do marked and slight mean? Then, many of the kids who visited Rahway had not been delinquents in the first place. If they had no apparent criminal tendencies, then it is not a great success that they didn’t go on to commit crimes. Moreover, the parents often received the letters within weeks of the visit, far too early to make a solid evaluation.

Another fundamental flaw he unearthed was that only those who responded to the questionnaire were included in the statistics. This seems a rather basic error. Imagine if your kid was mixed up in crime, you probably wouldn’t feel too enthusiastic about replying. You might well have felt embarrassed. This must surely have skewed the results. It reminds me of a TV programme here called Madrileños por el Mundo, which looks at people from Madrid who have gone to live and work abroad. Curiously the people they interview are all incredibly successful. If they are not running the Vienna Opera House, they are working for NASA. You never see the ones who are in badly-paid jobs or who ended up leaving. This is known as selection bias.

Ultimately, you need to know what would have happened if they hadn’t been taken to the prison. They might have done even better. There may have been another reason for them not committing crimes. This is where the randomised control trial comes in. you need to study one group which received the intervention and another that didn’t. This type of rigour generally seems to be missing from this kind of government initiative.

Finckenauer did exactly this and showed that the children who attended Rahway were more likely to commit crimes than those who did not. This is a bit counterintuitive. I watched the documentary and the sequel again on YouTube and it was just so convincing. Why wouldn’t it work? The idea that kids can be turned around with tough love is seductive. But we need to be aware of the danger of panaceas. The causes of juvenile crime are complex and to expect a three-hour visit to prison to be the solution is a bit naïve.  Finckenauer wrote:

The intentions of the inmates were genuine: they really wanted the kids to go straight. But the program was having unintended consequences. The experience of being shouted at seemed to be brutalizing the youngsters. Many seemed to be going out and committing crime just to prove to themselves and their peers that they weren’t really scared.

There is another amazing twist to this story. On January 1, 1982 a 19-year-old called Michele Mika was murdered in her bedroom; she was found with a 20-cm carving knife in her back After killing Mika, the criminal sexually assaulted for several hours. Not until more than 25 years had passed was anyone arrested. It was a 45-year-old Hackensack resident, Angelo Speziale, one of the 17 youngsters from the documentary. He had also appeared in the follow-up programme, where we see him with his wife and three kids. He claimed that the visit to Rahway had transformed his life:

“If I didn’t go to Rahway, I think I would have done hard time. I might not have my family. And my family to me right now is everything; it is the most beautiful experience in the world.”

Speziale, who had a job tiling floors, was caught by pure chance. After being arrested for shoplifting, the place obtained his DNA, which proved to be a match for the DNA of the sperm found in Michele Mika’s body. They had been neighbours in a duplex in the New Jersey city in 1982.

In this case I wouldn’t criticise the documentary. It is true that he did stab his victim. In the prison visit he had been made to read a newspaper article aloud about a prisoner who had been stabbed to death in his cell. You hear a frightened kid reading:

He was stabbed about a dozen times in the neck, chest, head and back. Robinson was pronounced dead on arrival at Rahway General Hospital.”

Angelo Speziale is now back in Rahway prison. The fact that he was responsible for a similar crime four years later may well have been a coincidence. We can’t be guided by one case. The problem with Scared Straight was the overall numbers. It was such a wonderful story, but it was be too good to be true. What you can criticise the show for is perpetuating this myth.

How chocolate can help you lose weight

June 6, 2015

Can you indulge your sweet tooth and lose weight at the same time? If it’s chocolate you crave, then the answer seems to be: yes. That is the surprising conclusion of a study by German researchers published this week in the International Archives of Medicine.

Confusion reigns in the diet world, with conflicting recommendations for diets that range from high-protein to low-carbohydrate and even high-fat. According to many nutrition researchers, the problem is that these tools are too blunt. “What is important is the specific combination of foods in your diet,” says lead author Johannes Bohannon, research director of the nonprofit Institute of Diet and Health. “Just lowering the proportion of carbohydrates is not a reliable weight loss intervention because it has different physiological effect depending on the bioactive compounds in your diet.”

Chocolate is a rich source of bioactive compounds, particularly a group of molecules called flavonoids, plant compounds associated with several positive health impacts. But teasing out the possible effects of such compounds in your diet, and how it may interact with various diet interventions, is rarely studied. It could be that simply consuming chocolate in combination with dietary interventions has no effect, or it could make such diets even more effective in the right dose.

To test the idea, the researchers divided volunteer human subjects aged 19 to 67 into three groups: One group followed a strict low-carbohydrate diet, another group followed the low-carbohydrate diet and also consumed 42 grams of dark (81%) chocolate per day, and a control group followed their status quo diet. Besides tracking their body weight and measuring blood chemistry before, during, and after the intervention, subjects filled out questionnaires to assess sleep quality and subjective well-being, a key predictor of dietary compliance.

As predicted, the low-carb group lost weight compared to the control. But surprisingly, the low-carb plus chocolate group lost 10% more weight. Not only that, but the weight loss persisted, compared to the low-carb group which saw a return of the weight after 3 weeks—a classic problem in dietary interventions known as the “yo-yo effect”. The chocolate group also reported better sleep and well-being, and their blood cholesterol levels were significantly reduced.

“To our surprise, the effect of chocolate is real,” says Bohannon. “It is not enough to just consume chocolate, but in combination with exercise and reduction in carbohydrates, our data indicate that chocolate can be a weight loss accelerator.”The researchers suggest that high-cocoa chocolate has the potential to enhance other diets as well. “The best part about this discovery,” says Bohannon, “is that you can buy chocolate everywhere, cheaply and without having to believe diet gurus or purchase expensive nutrition products over the Internet.”

Press release from The Institute of Diet and Health


Don’t you just love this press release? It is just the kind of thing to get some newspaper editors salivating and social media users sharing online. If it sounds too good to be true, I’m afraid it actually is. The chocolate-helps-you-lose-weight hoax was the brainchild of German television reporter Peter Onneken who pitched the idea to American journalist John Bohannen. They set out to prove how easy it was to get a dodgy scientific study published. In fact, the study did take place, but as we shall see, it was deliberately shorn of any scientific value.

Some people may find this unethical, but elaborate hoaxes are a tradition among sceptics. In previous posts I have mentioned how physicist Alan Sokal was able to get a bullshit article, Transgressing the Boundaries: Towards a Transformative Hermeneutics of Quantum Gravity, published in an American cultural-studies discussion journal, Social Text. The spoof piece was made up of ideas and quotations from various postmodernist philosophers and full of mathematical absurdities, which the editors failed to spot. I have also featured the magician James Randi, who coached stage performer José Alvarez to pretend he was channelling a two-thousand-year-old spirit named “Carlos”. And who can forget science writer Dr. Ben Goldacre’s dead cat, Henrietta, who became a certified member of the American Association of Nutritional Consultants after Goldacre paid $60 to the Clayton College of Natural Health?

For the experiment Bohannon claimed to be Johannes Bohannon, Ph.D., a health researcher and lead author of the study. Onneken and his collaborator, Diana Löbl handled the logistics. They had a few thousand Euros to recruit research subjects on Facebook. They also required the services of Gunter Frank, a German doctor responsible for running the study, and Alex Droste-Haars, a financial analyst, to massage the data. The study was intentionally flawed with a ridiculously small sample size, measuring 18 variables (weight, sleep quality, and cholesterol levels among others) that naturally fluctuate in participants. The 16 subjects (5 men and 11 women, aged between 9 and 67) chosen were from Frankfurt, and were paid €150 to go on a diet for 3 weeks. They were divided into three groups – one was a low-carb. Another was low-carb plus chocolate a bar every day, and the final one was a control group who were told to follow their normal diet. The participants had to weigh themselves every day for the three weeks, and the researchers also took blood tests, measuring all the variables you can measure from a drop of blood. The subjects also filled out surveys about their sleep quality and well-being and physical complaints.

By the end of the study they had a mountain of data. The control group’s average body weight fluctuated up and down around zero. Both of the treatment groups lost an average of around 2.5 kilos over the course of the study. But the people on the low-carb diet plus chocolate lost weight 10% faster, a statistically significant result. Moreover, the chocolate group had better cholesterol results and higher scores on the well-being survey.

The amount of data was of course one of the problems with the study. If you have a small number of people and a large number of variables that you’re testing for, you’re more or less guaranteed to find something that will appear to be statistically significant. It is a tried-and-tested recipe for false positives. And If you don’t say ahead of time what exactly you’re looking for, then you can just pick up wherever random result you do get and claim that you have made an important discovery. In this case what varied was the speed at which the participants lost weigh, but the result could have just as easily been that chocolate improves sleep quality or lowers blood pressure or cholesterol levels.

Now Bohannon and Onneken wanted to share their “scientific breakthrough” with the world. They needed to get their study published ASAP. As it was such patently bad science, they had to avoid any kind of peer review. They had the perfect solution. For €600 Euros published it in their premier journal, the International Archives of Medicine, an open access medical journal.

What happened then? It did get picked by the German newspaper Bild and Britain’s the Daily Star. It also made it on to Cosmopolitan’s German website and both the German and Indian websites of Huffington Post. On the other hand none of Britain’s broadsheets were fooled. Nor was the New York Times. The story also failed to appear on a major national network. However, I’m sure that this kind of material does frequently get through. Just go to Ben Goldacre’s website.

Curiously, the Facebook page for the International Archives of Medicine featured a statement from Carlos Vazquez the journal’s CEO, claiming the paper was published by mistake and was only live for hours:

Disclaimer: Weeks ago a manuscript that was being reviewed in the journal “Chocolate with High Cocoa Content as a Weight-Loss Accelerator” appeared as published by mistake. Indeed that manuscript was finally rejected, although it went online for some hours. We are sorry for the inconvenience. We are taking measures to avoid this kind of mistakes happens [sic] again.

This appears to be a terminological inexactitude as the paper appears appears to have been on a number of weeks. What’s more there is apparently this email from Vazquez:

I’m contacting to let you know your manuscript “Chocolate with High Cocoa Content as a Weight-Loss Accelerator” has been pointed by our editors as an outstanding manuscript and could be accepted directly in our premier journal *International Archives of Medicine.

Bohannen’s hoax raises questions about scientific experiments. This has been an ongoing theme in this blog. The abovementioned Ben Goldacre is a trenchant critic of such practices by the pharmaceutical industry. In “Missing Data“, the first chapter of Bad Pharma he shows the tricks employed by Big Pharma so that clinical trials will reach conclusions favourable to the drug company. He describes publication bias, in which only tests with important results are published. If a lot of tests with inconclusive results are ignored, this will skew the results. If the trial seems to be producing negative data, it may be stopped prematurely and the results not published, or if it is producing positive data it may be stopped early so that longer-term effects are not examined.

Ultimately we have to look at the role of the journalists. If you’re reporting on a scientific study, you need to actually look at the paper. You need to talk to a source with real scientific expertise. They need to actually interview the people behind the studies, and they should seek independent researchers’ opinions. And a healthy dose of scepticism wouldn’t go amiss.

10 Greatest Hoaxes of All Time

June 6, 2015

The Gloria Gaynor effect: are entrepreneurs deluded?

May 17, 2015

During World War II military engineers wanted to figure out how to make bomber planes safer for the pilots who risked their lives to fly them. These bombers were the fundamental to the allies’ strategic bombing, yet they were constantly being shot down over enemy territory. When the engineers looked at returned planes, they saw that bullet damage clustered in three main places: the wings, the body, and the rear gunner. These were the places they suggested be reinforced with extra armour. Fortunately for the army could call on the help of a statistician named Abraham Wald. His brilliant insight was that the holes from flak and bullets on the bombers that did return represented the areas that were actually able to take damage; a plane could get hit multiple times in the wings, body, and rear gunner and still continue flying. It was the planes that hadn’t returned that held the key to understanding where the problems lay –  it was the rest of the plane that needed reinforcement. I read this story on David McRaney’s blog You Are Not So Smart. It illustrates a logical fallacy known as survivorship bias.

Survivorship bias happens we concentrate on the people or things that survived some process and inadvertently ignore those that did not because we do not see them. This can lead us to over-optimism. We find survivorship bias in many areas of life. In business finance failed companies are excluded from performance studies, skewing the results. They would be very different if we included the businesses that failed. I previously mentioned this fallacy in a post about Warren Buffet. In Fooled by Randomness, Nasseem Taleb pointed out that while Buffet might well be an accomplished investor, a large population of random investors would almost necessarily produce someone with his track records just by luck. Taleb talks of a massive game of Russian roulette in which we only see the survivors.

Scott Fitzgerald, Mark Zuckerberg, Charles Darwin, Woody Allen and Steve Jobs all failed to finish university. Richard Branson, Thomas Edison, the Wright brothers Quentin Tarantino, and Bobby Fischer didn’t even finish school. Should we then stop compulsory schooling after the age of fourteen? Part of this phenomenon may be that the ones who failed academically took more risks. If you have a degree from a top university, you can walk in to many lucrative jobs. You have less incentive to take risks. Nevertheless, what we are seeing here is survivorship bias. In the United States over a third of each enrolled class of university students. drop out before graduation. While there may be a handful of outstanding successes, they will inevitably be a small proportion of those who dropped out.

In his book The Art of Thinking Clearly Rolf Dobeli sums it up nicely:

Behind every popular author you can find a hundred other writers whose books will never sell. Behind them are another hundred who haven’t found publishers. Behind them are yet another hundred whose unfinished manuscripts gather dust in drawers. And behind each one of these are a hundred people who dream of—one day—writing a book. You, however, hear of only the successful authors (these days, many of them self-published) and fail to recognize how unlikely literary success is. The same goes for photographers, entrepreneurs, artists, athletes, architects, Nobel Prize winners, television presenters, and beauty queens. The media is not interested in digging around in the graveyards of the unsuccessful. Nor is this its job. To elude the survivorship bias, you must do the digging yourself.

I also think it is important to look at both success and failure. It is vital to see the cases where it all went wrong. Were they doing things do differently? There should be bestsellers by people who have failed, but we don’t want to hear those stories. There are no easy lessons, I am sure that if you visit the graveyard of failed individuals and companies, you will find that many of those there possessed many of the same traits of the winners. This make sceptical about those books like 7 Habits of Highly Successful People or the ones that tell us lessons from this company or that corporate leader. We would need to create 20 Facebooks, which would all employ slightly different strategies.

Now we come to the second part of my post: are entrepreneurs deluded? When you see the statistics for business failures you would have to ask why people would believe that they can buck this trend. Entrepreneurs must surely be more optimistic than the rest of us. They must have the ability to shut out all the things that can go wrong. This may or may not be a delusion, but we really do need to cherish entrepreneurs. They are the risk takers. When things go wrong, they will take a big hit. How different it is from those too-big-to fail banks we have had to bail out in the last few years.

Missing what’s missing: a video on survivorship bias

May 17, 2015

This a TED video from David McRaney of the You Are Not So Smart. blog.


A contrarian’s provocative take on recycling

February 22, 2015

Annually we produce four billion tonnes of rubbish in the world. This factoid was quoted on the BBC World Service’s In The Balance podcast. The programme about recycling also featured a woman who is out to change all this. Lauren Singer, whose output of rubbish for the last two years would fit into an oversized jam jar. How was she able to accomplish such a feat?

It all began when Singer noticed a fellow Environmental Studies student bringing lunch to class every week with a single-use plastic bag, a disposable water bottle, and plastic takeout container. Seeing the irony of this behaviour, from someone supposed to be studying how to save the planet, Singer was sparked into action. She started to buy her clothes exclusively from second-hand outlets. She then set about making all of her own personal care and cleaning products. She decided to live a minimalist lifestyle, giving away all but her most essential possessions. She now runs a blog called You can see her being interviewed in the video below.

What she has been able to do is undoubtedly impressive. Nevertheless, there is one resource that is impossible to recycle, and she has been very profligate with it. I am referring to time. The amount of time required to live such a lifestyle, which involves making your own toothpaste for example, will take away from other areas of your life. This is indeed a zero-sum game. In fact, we all recycle every day of our lives. Economist Don Boudreaux has an essay entitled “I Recycle!”. Here is an extract:

After I awaken, I shower and dry myself with a towel that I’ve had for a few years. I use this towel day after day. I don’t discard it after one use. When it gets dirty, I toss it in the washing machine to clean it for further use. I recycle my towel.

Then I brew coffee and fix breakfast. Each day I use the same coffeemaker that I used the day before. I clean it after each use, recycling it for the next time. My wife and I drink the coffee from mugs that have been used many times in the past. (Actually, one set of our coffee mugs was handed down to us after my wife’s parents used them for several years.) We also eat our breakfasts using dishes and utensils that are recycled from countless past uses. After breakfast, we don’t throw our mugs, dishes, and utensils away; instead we put them in the dishwasher to be recycled for yet another use

After breakfast, I dress myself in clothes that I’ve worn before and that I will wear again. My underwear, my pants, my shirt, my necktie, my belt, my coat, my shoes, my wristwatch, all are recycled from previous uses. And when I remove these clothes at day’s end, I’ll recycle them again, with the help of our automatic washer and dryer.

When my wife and I drive to work, we drive automobiles that we used the day before and that we’ll drive for the next few years. We don’t junk them after a single use. Instead, we recycle them, day in and day out.

The pots and pans that we use to prepare our meals, our toaster, our refrigerator, our television, our compact discs, our furniture, and, indeed, our house itself are all routinely recycled, use after use after use.

My family and I recycle a lot! And we’re not alone. Everyone recycles a lot.

However, we do need to distinguish between what is a resource and what is rubbish. Mike Munger from Duke University put it like this:

There is a simple test for determining whether something is a resource (something valuable) or just garbage (something you want to dispose of at the lowest possible cost, including costs to the environment). If someone will pay you for the item, it’s a resource. Or, if you can use the item to make something else people want, and do it at lower price or higher quality than you could without that item, then the item is also a resource. But if you have to pay someone to take the item away, or if other things made with that item cost more or have lower quality, then the item is garbage.”

What I oppose is the notion of recycling as a moral imperative, a religious impulse if you will. The rationale seems to be recycling is always cheaper regardless of the cost. I, though, believe in trade-offs. We need to calculate the costs and benefits of each option. Recycling does not always save resources and it does not invariably protect the environment. Recycling is a manufacturing process and, like other manufacturing processes, produces pollution. Take the case of paper. You get toxins in both recycling and producing from scratch. Indeed, sometimes the recycling process actually has higher levels than the virgin manufacturing does. Moreover, recycling more paper will not necessarily preserve trees. If paper recycling reaches high levels, demand for virgin paper would go down. Remember Lionel Robbins’s classic definition of economics: the study of scarce resources and their alternative uses. Some lands being used to grow trees will be put to other uses.

There is another myth that without recycling regulations and laws there wouldn’t be recycling. This is the Guardianista take; there is no problem that can’t be improved by more government regulation. Let’s take the case of aluminium. When I was young you could demonstrate your masculine prowess by crushing a beer can in your hand. Now such a feat requires no great strength. What is behind this change? The high price of aluminium has provided companies with the incentive to reduce amount of aluminium in each can, making them lighter and easier to crush. Here is a clear example of the price mechanism motivating companies to use resources more efficiently.

There is another myth I would like to address – the widespread belief that we are running out of resources. When I was growing up experts said that we were running out of oil. However this is misleading. The amount of proven reserves is not fixed by nature at some immutable number. The key point is that when prices change, consumers and producers change their behaviour in response. Proven reserves are a reflection of the amount of a resource that can be recovered at current prices. When the price of a resource goes up, so does the incentive to find more or find alternatives. Consumers will also conserve more when the price rises. What’s more technological change makes new options viable. Thus it is absurd to look at current reserves or current consumption patterns as being immutable.

So here is my perspective on recycling. I do think that economics, with its emphasis on trade-offs, has a lot offer on environmental questions. Sure, there will be market failures, and government intervention may be required so that companies have to pay for the negative externalities of what they produce. But there is also government failure. Governments providing farmers with subsidised water and the recent ethanol debacle are examples of the government making ecological situations worse. I am not a climate change sceptic. But I do oppose these top-down solutions so beloved of the Guardian. By analysing the costs and benefits of each action, we will find better outcomes. I am pessimistic, however. I think to find an international consensus will be almost impossible.