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More or Less
20 Apr 12
00:27:46
We investigate the height of North Koreans, the width of police officers and rate of...
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- [00:00]
A
This is more or less the statistical spine of the otherwise floppy media. The programme now airs year round on the BBC World Service, but this is a full length episode from Radio 4. Hello and welcome to a new series of More or Less the programme that takes the numbers that surround us every day, turns them upside down and shakes them hard. This week we're looking at the height of North Koreans and the width of police officers. Lets start by looking back 20 years to the Earth Summit in Rio, when 172 governments met to debate global warming. They also opened a convention, now signed by 193 nations, to protect the world's biological diversity. Choosing a name for it was pretty easy. It's called the Convention on Biological Diversity. Actually, protecting diversity has of course proved to be a lot more difficult. You know, the dodo, the Falkland Islands wolf, the golden toad.
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B
Although they were all extinct before the Convention on Biological Diversity was created. More relevant examples are the Pyrenean ibex and the big river dolphin.
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A
Ah, Ruth Alexander's here. Just when I thought you were extinct, Ruth. Anyway, thanks. Yes. The Baiji river dolphin, the Pyrenean ibex, the panda.
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B
Pandas aren't extinct.
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A
It's just a matter of time, isn't it? They've got it coming. Ridiculously impractical creatures.
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B
We're not here to disrespect one of the world's cutest species.
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A
No, we're not. This is serious. I know it's serious because I spoke to the top man at the Convention on Biodiversity, Braulio Dias.
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C
It's a big problem. We know from certain sources of data that species extinction has increased in rate in recent times. So we know it is a problem. And we know that the drivers behind the species loss are mostly increasing. So land conversion and degradation, pollution, climate change, all these drivers are still around and increasing. And of course human population is still growing and consumption is growing. And most of that consumption is not sustainable.
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B
So there's a problem. And we're here to figure out how big a problem it is. How many species are actually going extinct.
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A
Now the Convention on Biological Diversity does put a number on it. Here's a quote from Brauley ODS Special Advisor Ahmed Joglav from the convention's website. We are indeed experiencing the greatest wave of extinction since the disappearance of the dinosaurs. Every hour three species disappear. Every day up to 150 species are lost.
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B
Doesn't that suggest there are 50 hours a day?
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A
Up to 50 hours a day, yes. I asked Ahmed Droglav's boss, Braulio Dias whether he could produce some slightly more rigorous numbers. And it turns out this isn't an easy question to answer.
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C
We started to identify species in a more scientific approach since Linnaeus about 250 years ago, and we're still doing it. Current estimates of number of species can vary from, let's say, 2 million species to over 30 or even 100 million species. So we even don't have a good estimate to an order of magnitude of precision.
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B
Actually, we can go back even further. In the 17th century, before Linnaeus was even born, the English naturalist John Rae was trying to work out the number of insect species.
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D
The butterflies and beetles are such numerous tribes, but I believe in our own native country alone, the species of each kind may amount to 150 or more. The fly kind will be found in multitude of species to equal if not exceed both the forementioned kinds. The creeping insects are also very numerous. Supposing then there to be a thousand sorts of insects in this island. If the same proportion holds between the insects native of England and those of the rest of the world, the species of insects in the whole Earth will amount to 10,000.
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A
Scientists have found about a million insect
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B
species since then, and they're discovering more all the time. 10,000 a year, by one estimate. You can laugh at John Ray for getting it so wrong, or you could stop to wonder whether future generations will laugh at us too. I went to meet Georgina Mace at London's Natural History Museum. She's a professor in the Centre for Population Biology at Imperial College London. And she accepts there's a lot of we don't know.
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E
Let's say there are somewhere around 7 to 10 million species on the Earth. That's an estimate we don't know exactly. Of those we've described less than 2 million. So the rest we don't know what they are. They have no names, we don't have descriptions of them.
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A
I think the problem goes deeper than that. Biologists don't even have a universally accepted definition of what a species actually is. Charles Darwin himself argued there will be times when it's impossible to say whether two animals are members of the same species or not. There are grey areas. Lots of definitions have been proposed since Darwin, some useful, but none of them totally resolve the issue.
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B
But the biggest problem probably isn't the definition of what a distinct species actually is. It's the sheer logistical challenge of counting them.
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A
And if we didn't know a species existed in the first place, we can hardly notice when it's gone.
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B
So there are two things you could do about that. You could create a mathematical model, or, as Georgina told me, you could count what you know has gone extinct, even though you may well miss a lot.
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E
The iucn, the International Union for the Conservation of Nature, has for many years maintained a list of threatened species. Now, if they're no longer around, they're called extinct. They've rolled off the end of that ladder to extinction, if you like.
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B
And how do they know if they're no longer around?
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E
Well, the criterion that the IUCN uses, which is this quite precautionary criterion, is that the species has consistently been looked for in appropriate places and at appropriate times and not been seen.
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B
Are we confident that they're looking in enough places?
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E
It's probably pretty good for birds and mammals. There's been a big effort over the last few years to ramp it up for amphibians and reptiles, but it's woefully inadequate. So that approach is never going to get us the answers we need.
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B
Now, the IUCN has A list of 801 species which have gone extinct last week.
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A
I thought it was 150 a day.
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B
No, 801 extinct species since the year 1500. Mostly animals, a few plants. But remember, this list comes from the subset of known species, not from the huge variety of unknown species out there, which, as Brauley O' Deer said, could be up to 100 million, which makes
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A
it sound like the whole thing's complete guesswork.
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E
Georgina, it's not exactly guesswork, it's modelling. What you then do is go, well, okay, let's not try and count species one by one, and they're all their individual members one by one. Let's take an approach where we look at the pattern of species distribution over the world. We look at the habitat they're dependent on, and we look at rates of change in those habitats and make some extrapolations based on that. If you do that, you end up with these very high rates.
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A
Now, that model applies something called the species to area relationship to habitat loss. The simplest possible way to describe it is like an estimate is made of the number of species in a given area or habitat. The larger the area, the greater the number of species are said to be in it. Then the model gets worked backwards. The smaller the area, the fewer species are said to be in it. In other words, if you measure habitat loss, you can calculate, using the model, how many species must be being lost in that area, even if you don't know what those species actually are.
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B
It's this model which, as Georgina says, has generated some very alarming numbers. But more recently, it's also generated a mathematical row, thanks to this man.
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F
My name is Stephen Hubble and I'm a distinguished professor at the University of California, Los Angeles and also a senior staff scientist at the Smithsonian Tropical Research Institute.
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B
Professor Hubble thinks that let's call him Stephen. Stephen thinks the species to area relationship model relies on poor maths. And as a result, he says there's a problem.
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F
Well, for the past 40 years people have been using a method that we show as biased and it's biased too high, I.e. it overestimates the extinction rate. The basic problem is that there is an expected relationship as you increase area with an increasing number of species found in the area. And people thought, well, it's straightforward just to run that curve backwards, reduce the area as if you were cutting down forest and losing habitat to find out how many species would be left. The problem is that we have modeled the species area curve by something called a power law.
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A
Let's pause there a second. We're not going to get into what we mean by a power law. The point is that the relationship doesn't work the same way in reverse.
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F
Well, it turns out that the method, when extrapolated backward, doesn't take into account the fact that you need to remove more area to get the whole range of a species. Then you need to remove area to find the first individual of species.
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B
In other words, Stephen says the model assumes that if you add say a hectare to your five hectare field, then you'll find say five new species. And that that means that if you reversed the process and shrank the field, you'd lose five species. Stephen says that's not how it works. That in fact you need a larger area to eliminate a species than you do to discover one. He says if you correct the mistake in the model, you, it shows about half as many species are going extinct.
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A
And Professor Hubble did make, Stephen did make another interesting point about what kinds of species we're talking about in all this. He said that while many of us thinking about extinction might have in mind so called charismatic animals like rhinos or whales or those ridiculous pandas, in fact, the overwhelming majority of species in the world aren't like that. Only a tiny fraction even have backbones. Many are microscopic and most aren't even named. He said we think too much about the beautiful animals.
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F
Statistically we overcount them all the time because we care about them. That is, the proportion of the world's species that are charismatic organisms is really tiny. You know, from a Biomass point of view, this is a bacterial planet. There's more biomass and bacteria than all other life combined. Now, should we care about that? Well, bacteria run the world, they run our gut systems, they help us to digest food, etc. Etc. So, yes, it's a very parochial view to assume that we should care only about elephants and zebras and not about bacteria.
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A
I think one of the problems for many people trying to call attention to species loss is that while perhaps it's true that we should care about bacteria, most people care a lot more about the charismatic animals. And there just aren't many examples of those kind of animals going extinct. Ralio Diaz agrees with Stephen Hubble that we shouldn't focus too much on big furry animals. But even so, it was striking that when I asked him to name something that had actually gone extinct in the last few years, he struggled.
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C
You only have to look at the IUCN data set at global level to realize there have been several species that have gone extinct in the last century. For example, I can give you examples of Brazil, where I came from. We have some species of macaws that are very threatened. There's one particular species called the Spix macaw, where the population went extinct in nature. Fortunately, there are still a few individuals kept in captivity and reproducing, so there's still hope in the future to increase their numbers and be able to return them to the wild habitats.
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A
However you look at all this, it's obvious that no one can safely quantify what's going on. When Ahmed Joghlav from the Convention on Biological Diversity told The every hour three species disappear, every day up to 150 species are lost. He couldn't possibly know that to be true, whichever one of those two statements he actually meant. In fact, it seems that any firm number put on species loss, however big or small, is going to be spuriously precise. We just don't know.
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B
But let's be clear. Everyone we've spoken to in researching this item thinks there is a problem. That includes Stephen Hubble, who says he worried about whether disputing the numbers would make people complacent about species loss. In the end, though, he thought it was more important to share what he'd found.
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F
My bigger worry is that scientists not use flawed methods, because I am a scientist, so I am concerned that we give the most accurate methods a chance to work, rather than ones that we know to be flawed. So when you find a mistake, you are, as a scientist, obligated to notify everyone that we've made a mistake and we need to fix things. And so, yes, there's been a reaction from my colleagues about this. We were warned by some of them not to publish our paper, but that's not advice that I felt I was morally able to take.
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A
Stephen Hubble of the University of California, Los Angeles, and of course, Ruth Alexander. You're listening to More or Less with me, Tim Harford. While we were off air minding our own business, a man called Cliff emailed us at our usual address, more or less@BBC.co.uk. in the expat papers here in Thailand, there was a factoid circulating that more British tourists die in Thailand than in any other tourist destination.
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G
Hmm.
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A
As we all know, a factoid is not quite a fact, just as a humanoid is not quite a human. I'm assuming Cliff is a loyal listener rather than a mere listener. Oid. Although I cannot know for sure. But what I do know for sure is there's a simple way to find out how many Brits die in Thailand. The Foreign Office collect data on British deaths abroad, and Linda St. Cook is part of their Know before youe Go campaign, which offers advice on staying safe overseas. I asked Linda whether it's true that more Brits die in Thailand than any other destination.
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H
No, actually, more British people die in Spain than anywhere else in the world.
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A
Presumably this is something to do with the fact that there are lots and lots of British holidaymakers in Spain, lots
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H
of British holiday makers and lots of British residents. So, last year, in the financial year 2010-11, 16, 39 British nationals were reported to our consular staff as dying in Spain. But the majority of those were of natural causes, 73%.
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A
Okay. Well, I suppose it's not entirely okay if you're one of those people. Proportionately, what is the riskiest place? What is the place where, if you go on holiday, you are most likely to end up not coming home?
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H
The Philippines is the place with the highest proportion of deaths to British residents and holidaymakers. And actually, it's more residents than tourists. We have quite a high population of elderly, retired British people living in the Philippines. And so 84% of people whose deaths are reported to us in the Philippines are from natural causes.
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A
So Spain is top in terms of the absolute number of people dying. The Philippines is top in terms of. These are not really league tables you want to top, but the Philippines is top in terms of the proportion of British residents and visitors dying. Is Thailand anywhere near the top of either of those lists?
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H
Yes, Thailand is not near the top in number terms, but it. It is second, I'm afraid, to the Philippines in proportional terms.
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A
So it's conceivable that there was a time when it was top.
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H
Oh, yes, I think that's very conceivable.
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A
Do we know anything about the unnatural causes? Do we know what is causing people to die in Thailand, Spain, France, if they're not just dying of old age?
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H
I think actually it's going to be quite difficult for me to give you a proper answer to that because we can't always be sure that all of our statistics are completely comparable from one country to another. So it probably wouldn't be very fair of me to try to give you a partial answer on that.
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A
But we do have statistics on arrests, which I suppose is one sort of measure of getting into trouble.
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H
Absolutely. In terms of the highest actual number of arrests last year that took place in Spain. But again, that's probably going to be down to the very large number of both resident and visitor numbers.
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A
All the East End gangsters retiring to the Costa del Sol.
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C
Right.
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A
If I can refer to a caricature there.
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H
But actually, proportionally, people are more likely to be arrested in Thailand than anywhere else. Followed by the state.
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A
Linda St. Cooke and if you like, Cliff, have a factoid you'd like us to check out, please email us at more or lessbc.co.uk now. One place I think it's safe to say has few British visitors is North Korea. The world's most reclusive nation is in the news yet again thanks to its recent failure to launch a long range rocket, an embarrassment for the country's new leader, Kim Jong Un. What was supposed to be a symbol of power has become a symbol of impotence. But a statistic has been doing the rounds, which is as resonant as any misfiring missile. The Independent reported last week that nothing is small in North Korea apart from the people who are on average 3 inches shorter than their cousins in the South. It's just the latest version of this claim. In 2010, the late Christopher Hitchens put the difference at 6 inches in an article entitled A Nation of Racist dwarves. Senator John McCain referred to a three inch gap in a 2008 presidential debate against Barack Obama. Three inches is about seven and a half centimeters, by the way. For those of you listening, in metric, 6 inches is more than 15 centimeters. So what's the truth? 7 and a half centimeters. 15 centimeters. Professor Daniel Schwecendiek from Sunkyun Kwan University in Seoul has the answer.
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I
I conduct a statistical analysis with data from North Korean Refugees measured upon their arrival here in South Korea. There are several 10 thousands of refugees by now here in Seoul. And according to the results from the refugee surveys, the height GAP is approximately 4 cm among preschool boys and 3 cm among preschool girls. The South Koreans would be taller than the North Koreans. In addition to this, I also conducted statistical comparisons with adults and we look at 20 to 49 year old north Korean men and compare them to their South Korean counterparts. I find height gaps of 3-8 cm and 1-6 cm among women. And again, of course, the South Koreans were taller.
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A
What are the consequences for North Korean refugees living today in South Korea?
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I
Yeah, that's a big problem because height doesn't really recover from if you were extremely exposed to famine. Which means that the North Koreans that enter South Korea, even though they are living in a very healthy and wealthy environment here, their height doesn't recover much. The weight recovers, but not their height. And if you look at older Koreans, we now face a situation where the average South Korean woman is approaching the height level of the average North Korean man simply because of the excellent living conditions here in the southern part of the peninsula, as opposed to North Korea that, as you know, experienced a famine in the 1990s. So this is, to my knowledge, unique situation where actually women become taller than men.
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A
Professor Schwecendik says data from inside North Korea, collected both by the North Korean government and by international organizations working there, appear to support his findings. He also told me the height difference can't be attributed to genetics because the two populations are basically the same.
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I
That's exactly the interesting thing. We can basically rule out genetic influences biasing the findings because we're dealing with the Korean people. And Korea is a very interesting nation because it hasn't experienced immigration for many centuries. It was labeled Hermit Kingdom, which in the case of North Korea still pertains today. But even South Korea wasn't impacted much by immigration until the 1990s.
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A
Martin Blum is head of nutrition at the World Food Programme, which has been providing food aid to North Korea since 1995. He says it's clear that poor diet in the early years of life leads to stunted growth.
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G
Of course, the food and what happens in the first two years of life is actually critical for people's height later. Economic growth is one of the main determinant of height improvement. A good example is the Dutch height. If you think about just before the war, 1938 or so, the height of the Dutch man was about 1 meter 65. It was about 10 centimeters less tall than the US. In 1955 we were about 10 centimeters taller, about 175, the average man. And nowadays we are the tallest in the world, which is about 186. So in the period of about, I would say 70 years or so, 70, 80 years, we became 20 centimeters taller. And that of course had a lot to do with the type of food people were consuming, particularly in the first two years. We know that that's actually because what we call stunting is actually happening very early in life, but has long term consequences.
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A
Martin Bloom, a strapping fellow from the Netherlands. In the 1990s, North Korea suffered a terrible famine. Even today, according to the World Food Programme, one in every three children remains chronically malnourished or stunted, meaning they're too short for their age. So it seems that this statistic reveals a tragedy, that as South Koreans are getting richer and taller, North Korean children are being stunted by lack of food. You're listening to more or less in association with the Open University. Time for a change of mood. I think.
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C
I know a fat old policeman he's always on our street A patterned jolly
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D
red faced man he really is a
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C
treat he's too kind for a policeman
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D
he's never known to frown and everybody
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C
says he is the happiest man in town.
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A
Reading the headlines last month, you may have thought the description of the red faced fat policeman might have been truer than you ever imagined.
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D
The blobby bobbies of Scotland lard.
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A
Three quarters of male met staff are overweight.
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B
52% of male metropolitan police officers are overweight. When the police are significantly fatter than the population as a whole, there is a problem that needs to be addressed.
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A
Hang on, is it 52% that are overweight or is it three quarters?
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J
I know these figures are laughable. I don't think the police found it very funny though.
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A
Wesley Stevenson's here.
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J
Hi, Tim.
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A
Hi, Wes. So 50% of the MET aren't overweight?
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J
No. And the other person who's not laughing is Tom Windsor, whose report these figures came from.
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K
This was materially misleading because that's not what the data which we published showed. What we showed was that there had been a sample taken of Metropolitan Police officers who were self selecting sample who came forward for a special health check, perhaps because they were individually concerned that they might be overweight or in other ways unhealthy. And about 11,500 police officers and police staff had the health check. Of that, just over 7,000 or 61% were police officers.
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A
So what we should be saying is that if you look at a self selecting sample of Metropolitan Police employees, the majority, but not all of whom were police officers, if you look at this sample of people who are concerned about their health and who went for a checkup, more than half of them were overweight.
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J
Yes, that's right.
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A
That's not going to make a good headline, is it? In fact, I'm not even sure it made a comprehensible sentence.
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J
No. And if you look at the piece in the Mets in House magazine advertising the health checks at the time, it states that they could make your extra pounds disappear. And it said that the programme offered a complimentary health Check and a 12 week exercise and diet programme.
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A
So only 60% of people who answer an advert offering to help them lose weight are actually overweight. I'm surprised the proportion isn't a lot higher. Obviously these figures are wrong and the papers should be more careful.
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J
Well, they should, but the Windsor report, I think is in part to blame here. In there, it compares the information from this self selecting sample from the Met with the population as a whole, which of course is representative and bears no relation to the Met figures. I put this to Tom Windsor.
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K
I think that may have led to some journalists with tight deadlines going for the headlines that they did. The difficulty that we had is this is the best comparison we were able to make. But yes, I can see how it could have been misinterpreted. In fact, the context of the figures and the comparisons that we were making were very precisely explained in the report. It's just that that explanation seems to have been brushed aside and a completely misleading picture presented.
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J
Do you think it was a mistake to compare these two figures at all?
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K
No, I don't, because it was the best comparison that we could have made.
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A
We must be able to tell something from these figures.
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J
Yes, we can. I mean, although this isn't a representative sample, it is large and includes around 22% of the MET's officers. So even if most of the overweight people in the sample were actually Met staff rather than officers and you discounted them, you would still be left with 2,900 people who would all be overweight Met officers, which is nearly 10% of the force. Although this is substantially lower than the general population where around 60% are overweight.
- [26:18]
A
So at a bare minimum, it's at least 10%. And that's the best data we have.
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J
Yes, I mean, the truth is we simply don't know how fat or otherwise the police force in this country is. And for most officers, once they've joined and passed their fitness test, they don't get retested unless they're in a specialist area such as firearms. And one of Tom Windsor's complaints is that the data for a lot of the areas he was trying to investigate simply wasn't there.
- [26:41]
K
I used to be the regulator for the railways, and when I took that office in 1999, I was startled by the poor quality data that Railtrack in particular had about the condition, capacity and capability of its assets. I'm afraid that when compared to the railways, the police come out pretty bad.
- [26:58]
A
Tom Windsor, who conducted the independent review on police pay and conditions, and Wesley Stevenson. Thanks, Wes. And that's all we've got time for this week. I'm off for a strict diet of true facts and straight statistics for the next few days, but no doubt there will be junk science and bloated press releases waiting for me to devour before much longer. If you see a fact you'd like us to check out, or a fascinating statistical odyssey on which you'd like us to embark, drop us an email at more or lessbc.co.uk. our website is BBC.co.uk more or less the place to subscribe to our podcast. Or you could simply tune in same stat time, same stat channel next week. Goodbye. More or Less was presented by me, Tim Harford, the undercover economist at the Financial Times. The producer was Richard Knight and the editor, Richard Varden.