More or Less

Is dementia on the rise? Plus immigration, incomplete contacts and chocolate muffins

Sexual violence was widespread in Liberia’s brutal and bloody year civil war. But were three quarters of women in the country raped? We tell the story behind the number and reveal how well-meaning efforts to expose what happened have fuelled myths and miss-leading statistics that continue to be propagated to this day, including by the UN.

We speak to Amelia Hoover Green from Drexel University, Dara Cohen from the Kennedy School of Government at Harvard University, researcher Phyllis Kimba and Aisha Dukule from the think tank Center For Liberia's Future in Monrovia.

(Photo: Liberian women and children wait for rice rations in overcrowded Monrovia, June 2003. Credit: Georges Gobet/AFP/Getty Images)

Who voted in the US elections? Plus are there nine million stray cats in the UK?

Does the world really spend three times as much on ice cream than on humanitarian aid?

The fact-checkers have been working overtime looking into the numbers used by Donald Trump during his campaign to become President of the USA. In the wake of the election next week, we take a look at some of Trump’s more outrageous statistical claims

Is a girl under 15 married every seven seconds? And beware dangerous algorithms

How many people die for every kilo of cocaine? More Or Less investigates.

When maths can get you locked up.

It’s now a year since the UN set its new Sustainable Development Goals to try to make the world a better place. They include 17 goals and a massive 169 targets on subjects like disease, education and governance. But some people like Bjorn Lomborg are saying that there’s just too many and they are too broad, and left like that will never achieve anything. Is he right – and is there a better way to make the world better and stop some countries lagging behind? Wesley Stephenson and Charlotte McDonald find out.

Polling on the first TV debate between Hillary Clinton and Donald Trump appears to be divided over who won it. But not all polls are equal. If the people being polled aren’t representative of the population at large, then their responses may not tell you anything useful. And when internet polls can be hijacked by online activists, they can throw up some pretty strange results.

(Photo: Donald Trump and Hillary Clinton first presidential debate. Credit: Getty Images)

This week Donald Trump claimed that there are some inner city areas in the US which are suffering from the worst crime rates ever. They are so dangerous, he says, that Afghanistan is safer than many of these areas. But could this be true? We take a look at crime in the US and assess whether you can compare it to a conflict zone such as Afghanistan.

(Image: Chicago - Neighbourhood residents watch as police investigate a homicide scene. Credit: Scott Olson/Getty Images)

Can economics help us work out the perfect amount to spend on a wedding gift? Our reporter Jordan Dunbar is in a tricky situation-he’s heading to an old friend’s wedding and needs to figure out how much to give as a gift without breaking the bank. Luckily, economist Maria Kozlovskaya is on hand to talk about her findings on what factors we need to consider for gift giving, as well as preserving Jordan’s friendship and wallet.

Over the last two months the Government in the Philippines has been encouraging the police to clampdown on the illegal drug trade. The new President, Rodrigo Duterte, went as far as saying that citizens could shoot and kill drug dealers who resisted arrest, and the killings of drug suspects were lawful if the police acted in self-defence. The press have been reporting numbers of how many people have been killed during the crackdown – but how much trust can we put in these figures?

Lottery wins We interview Adam Kucharski, author of The Perfect Bet, to find out if maths can give you an edge to playing the lottery or gambling.

It is a commonly held belief that if women spend enough time together, their bodies start to communicate through chemical signals, known as pheromones. Eventually the women’s bodies will start to menstruate at the same time.

But where does this idea come from? And is it really true? We look at the evidence and wonder – could it be down to chance?

Britons entitled to Irish passports After the Brexit vote in June, so many Britons applied for Irish passports that Ireland’s foreign minister had to ask them to stop – pointing out that the UK remains, for now, in the EU. If some of the figures that have been quoted are correct, the Irish passport service may find itself completely inundated in future. But does one in four Britons really have Irish heritage? We reveal the dubious history of that number and attempt to estimate the number of Britons who are actually entitled to dual nationality with Ireland.

Do women’s periods sync? It is a commonly held belief that if women spend time together, their bodies start to sync and they will have their periods at the same time. But where does this idea come from? And is it really true? We look at the evidence and wonder – could it be down to chance?

Numbers in music Marcus du Sautoy takes us on a journey through some of his favourite musical pieces, pointing out the interesting mathematical patterns hidden in the compositions.

Dangerous algorithms Cathy O’Neil, a data scientist and activist, has written a new book, “Weapons of Math Destruction.” She is concerned about the proliferation of certain kinds of algorithms – that help make important decisions, but that could be based on unfair statistics with hidden biases. She explains how to look out for them, and what we can do to protect ourselves.

Desk of Good News – organ donations We look at the trends for organ donations and transplants.

Statistics suggest that officially about half of the countries in the world have abolished Capital Punishment, and a further 52 have stopped its use in practice. But we tell the story behind the numbers and show why the picture is more complicated. We speak to Parvais Jabbar, co-director of the Death Penalty Project.

The “gender pay gap” This topic has been in the news this week after the Institute for Fiscal Studies published research showing women end up 33% worse off than their male counterparts after they have children. But earlier in the summer, Fraser Nelson wrote in the Telegraph that the pay gap is “no longer an issue” for women born after 1975. Can both assessments be true? And could the label “gender pay gap” be hindering our understanding of what really lies behind the numbers?

The cost of a hospital If a politician or commentator wants to underline just how wasteful a piece of expenditure is, a common strategy is to compare it to the number of hospitals you could build instead. Of course, hospitals are positive things – we all want more, right? But just how much is a hospital? Is it really a useful unit of measurement? We speak to health economist John Appleby.

Corbyn Facts As Labour members begin voting on the party leadership, we investigate some of the claims made on the “Corbyn Facts” website set up by Jeremy Corbyn’s campaign. Did he really give 122 speeches on the EU referendum during the campaign? Were this year’s local election results as good as Labour’s best performance under Ed Miliband? We look at what the numbers tell us.

Death Penalty abolition Statistics suggest that officially about half of the countries in the world have abolished Capital Punishment, and a further 52 have stopped its use in practice. But we tell the story behind the numbers and show why the picture is more complicated. We speak to Parvais Jabbar, co-director of the Death Penalty Project.

The Holiday Desk of Good News This week we outline a handful of statistics to make everyone feel better about the UK and their holidays.

With high profile attacks in Brussels, Nice and Munich, you might think that 2016 has been a particularly bad year for terrorism in Europe. But what happens when you put the numbers in historical context and compare them with figures for the rest of the world? More Or Less hears from Dr Erin Miller of the Global Terrorism Database and Harvard psychology professor Steven Pinker.

(Image: A man wrapped in a Belgian flag holds a candle as people gather at a makeshift memorial on Place de la Bourse two days after a triple bomb attack hit. Credit: Philippe Huguen/AFP/Getty Images)

Is 2016 an unusually deadly year for terrorism?

In a joint investigation with BBC Newsbeat and BBC Monitoring, we’ve analysed nearly 25,000 news articles to assess whether 2016 so far has been a unusually deadly year for terrorism. It certainly feels like it. But what do the numbers say? We estimate that, between January and July this year, 892 people died in terrorist attacks in Europe – making it the most deadly first seven months of a year since 1994. But the vast majority of those deaths have been in Turkey. The number for Western Europe is 143, which is lower than many years in the 1970s.

Dying ‘at the hands of the police’

This week retired footballer Dalian Atkinson died after being 'tasered' by police. His death has renewed concerns about the number of people who die after coming into contact with the police. Recently it was claimed that one person a week dies ‘at the hands of the police’ and that ‘black people are disproportionately affected.’ We take a look at the numbers.

Olympic predictions

As the Games in Rio draw to an end, we look back at the medal predictions we made before they started. Which countries have performed as expected? And which failed to meet our expectations?

The cost of a wedding gift

Can economics tell us how much to spend on a wedding gift? Our reporter Jordan is in a tight spot. He’s heading to an old friend’s wedding and needs to figure out how little he can get away with spending on a gift. Luckily, economist Maria Kozlovskaya is on hand to explain her findings on our ‘internal exchange rate’ for gift giving. Can she preserve Jordan’s friendship while protecting his wallet?

World Records are being set at a much faster rate in swimming than in other sports. At the Rio Olympics, British swimmer Adam Peaty managed to break the men's 100m breaststroke world record twice in two days. Tim Harford speaks to swimming coach, Rick Madge, about the reasons swimmers keep getting better results in the pool.

Also, science writer Christie Aschwanden makes the case for the virtues of the 5,000 metre race. She says that in recent times it has become very popular for people to train to run a marathon. But when you look at the numbers, is the 5K a better distance?

Presenter: Tim Harford Producer: Charlotte McDonald

It has been reported that Prime Minister Theresa May is planning on lifting the ban on creating new grammar schools. Chris Cook, Policy Editor for Newsnight, has been looking at the evidence for whether these selective schools improve exam performance or social mobility.

Swimming World Records New world records are being set in swimming at a much faster rate than other sports – but why? Tim Harford speaks to swim coach and blogger, Rick Madge about the reason swimmers keep getting better results in the pool. Why do other sports, like athletics, not seem to have the same continual improvements in results?

Teenage girls aren’t so bad after all This week’s Desk of Good News challenges the concept that teenage girls and young women are badly behaved. It features statistics on falling teenage pregnancy rates, drinking figures and improving educational success.

The rise of TV Was the Queen's Coronation the event that sparked the biggest rise in TV sales ever? We take a look at the rise of television in the UK.

Lottery wins Adam Kucharski, author of The Perfect Bet, looks at the maths behind playing the lottery or gambling.

Presenter: Tim Harford Producer: Charlotte McDonald

How can we use statistics to predict how many medals each nation will win? We speak to Dr Julia Bredtmann, an economist at the RWI Leibniz Institute for Economic Research. She has come up with a model to predict how many medals each country will win, along with her colleagues, Sebastian Otten, also from the Leibniz Institute, and Carsten Crede of the University of East Anglia.

Some countries like the US and China have a large population and GDP, but a number of countries do very well for their size and wealth. Julia explains the different factors you have to consider to predict Olympic success.

The Government says that since the introduction of the 5p fee for single use plastic bags their use has plummeted. We take a look at the numbers.

Olympic Medals at Rio 2016 The Olympic Games are with us again. So how can we use statistics to predict how many medals each nation will win? We speak to Dr Julia Bredtmann, an economist at the Leibniz Institute for Economic Research.

Income inequality Politicians and commentators often claim that the rich are getting richer while the poor are getting poorer. But what do the numbers actually tell us about income inequality in the UK? Tim Harford interviews Jonathan Cribb of the Institute for Fiscal Studies, the co- author of a comprehensive analysis of Living Standards, Income Inequality and Poverty in the UK.

Desk of Good News – Maternal mortality rates The number of women dying in childbirth is falling around the world. In 1990, maternal mortality rates were 385 deaths per 100,000 live births Today there are 216 deaths per 100,000 live births. This means the death rate is down by nearly half.

The Coastline Paradox Why is it so difficult to measure coastlines? The further you zoom into the detail of a coastline, the longer it becomes. This is referred to as ‘The Coastline Paradox’. We speak to Mairi Walker, a mathematician at the University of Edinburgh, and Danny Hyam, from The Ordnance Survey - the UK government agency responsible for mapping our coastlines.

How can the techniques of computer science help us in everyday life? We speak to Brian Christian co-author of ‘Algorithms to Live by: The Computer Science of Human Decisions’. He argues that the techniques of computer science can help us manage everyday situations in a more logical and efficient manner. So which algorithm can help solve the problem of odd socks? And what is the most efficient way of alphabetising your book collection? Tim Harford investigates.

Many news outlets have reported this week that a Waitrose supermarket pushes up house prices in the surrounding area. It’s based on research that also suggests that other supermarkets have a similar but smaller effect. We take a highly sceptical look at the correlation.

Statistics and the EU referendum campaign We look at how the two campaigns, the media, and the much-discussed “experts” used statistics during the EU referendum campaign. Tim Harford interviews Will Moy, director of Fullfact, and Paul Johnson, director of the Institute for Fiscal Studies.

Antiques Roadshow BBC One’s Antiques Roadshow is a hugely popular television programme, where experts examine and value antiques and collectables. We ask whether the items featured really jump in value, or are we just seeing the price tag rise over the centuries in line with inflation? More Or Less reporter Charlotte McDonald heads down to the show to find out.

Computer Science and Socks Tim Harford speaks to Brian Christian, co-author of ‘Algorithms to Live by: The Computer Science of Human Decisions’. How can the techniques of computer science help us in every-day situations? And, most importantly, which algorithm will help our reporter Jordan Dunbar sort out his socks?

The Irish Central Statistics Office has released figures showing that Ireland’s economy grew by 26% in 2015. That would make it the fastest growing economy in the world. But American economist Paul Krugman described this as “leprechaun economics” as this growth rate is so unrealistically high. More or Less explores how multinational companies with headquarters in Ireland have led to an accounting headache for working out the country’s GDP.

Also, the mobile gaming app Pokemon Go has taken the US by storm and is now spreading across the world. But does Pokemon Go really have 26 million daily active users in the US? More Or Less investigates.

Protests have spread across the United States over the last few weeks. The protestors have been registering their feelings about incidents where police have shot and killed black men. High profile recent incidents resulted in the deaths of Alton Sterling and Philando Castle, and the protestors feel that minorities are being disproportionately targeted by the police.

On top of this, at a recent protest in Dallas a gunman shot and killed five police officers.

But what can the numbers tell us about the issue? How many people do police officers kill each year in the USA? And how many police officers are killed? Tim Harford investigates.

Producers: Charlotte McDonald, Elizabeth Cassin

It’s often said that we should all be aiming to get eight hours of sleep a night. But could it actually lead you to an early grave? Research shows that sleeping for longer, or shorter, than average is associated with an increased risk of disease and mortality. But what’s causing the health problems, and should you really give up the lie-in? Ruth Alexander looks at the latest sleep science with Dr Gregg Jacobs from UMASS Medical Center, US; Professor Franco Cappuccio from Warwick University, UK; Professor Jim Horne of Loughborough University, UK; and Professor Shawn Youngstedt of Arizona State University, US.

*Please note this is a repeat from February 2015*

(Photo: Man asleep in a bed. Credit: Corbis)

Is Iceland the best football team in the world per capita? England suffered a 2-1 defeat to Iceland in the European Football Championship in France. This was embarrassing for England when you consider its population is 163 times bigger than Iceland’s. We take a look at whether Iceland is now the best performing football team in the world if you compare UEFA ranking to the size of each country’s population. Plus, we take a look at the chances of a young man in Iceland and in England getting to represent their country on the pitch.

Old versus young Brexit voters

Many media outlets have reported that it was predominantly the older generations in the UK who voted to ‘Leave’ the EU in a recent referendum, while those under 25 were keenest to ‘Remain’. It has prompted many listeners to ask whether a referendum on this topic might yield a different result if held in a few years’ time as the electorate changes. We attempt some back of the envelope calculations with Tom Chivers from Buzzfeed. But actually – how good is the data available? How do we know how people voted or how they would vote in the future?

Following a referendum, the UK has voted to leave the European Union. Tim Harford and the team explore what that might mean for the UK’s economy. Most notably - what might be the impact on trade? We examine the economic forecasts from the government, and how the UK might manage its relationships with other countries.

(Image: A pay-per-view binocular with the British and European Union flags. Credit: Sean Gallup/Getty Images)

How are companies using our personal data? It’s a familiar concern. Online retailers are tracking us so they can sell things to us. Bricks and mortar retailers have loyalty card schemes. Our banks and credit card companies know all about us. And of course, the big computer and telecoms companies could potentially track our internet searches, our phone calls – even our location as we wander around. But this isn’t the first time that large corporations have gathered sensitive data about their customers. We tell the shadowy story of how the personal details of Americans were pooled among insurance companies more than a hundred years ago. Presenter: Tim Harford Producer: Elizabeth Cassin (Image: A police CCTV camera observes a woman walking. Credit: Leon Neal/AFP/Getty Images)

If it seems the EU referendum debate just involves two politicians shouting contradictory statistics at each other - then we are here to help. In this series, we're giving you a break from the politicians and we're going to try to figure out the truth. Bracing concept, isn't it? We'll be looking at some of the big questions - the cost of being a member, immigration, lawmaking and regulation. But today we're looking at trade. Tim Harford asks if the UK would be better off in or out when it comes to trade with other nations.

If it seems the EU referendum debate just involves two politicians shouting contradictory statistics at each other - then we are here to help. In this series, we're giving you a break from the politicians and we're going to try to figure out the truth. Bracing concept, isn't it? We'll be looking at some of the big questions - the cost of being a member, immigration, law-making and trade. But today we're looking at EU regulation. Tim Harford asks how much red tape from the EU is costs the UK and what might happen if we leave?

If it seems the EU referendum debate just involves two politicians shouting contradictory statistics at each other - then we are here to help. In this series, we're giving you a break from the politicians and we're going to try to figure out the truth. Bracing concept, isn't it? We'll be looking at some of the big questions - the cost of being a member, immigration, regulations and trade. But today we're looking at lawmaking. Tim Harford asks how much UK law comes from the EU and are we always being outvoted on what to implement?

If it seems the EU referendum debate just involves two politicians shouting contradictory statistics at each other - then we are here to help. In this series, we're giving you a break from the politicians and we're going to try to figure out the truth. Bracing concept, isn't it? We'll be looking at some of the big questions - The cost of the EU, lawmaking, regulations and trade. In th secomd of these programmes Tim Harford asks what might happen to migration if we left the EU, and what are the benefits and costs of EU migrants to the UK economy?

If the EU referendum debate just involves two politicians shouting contradictory statistics at each other - then we are here to help. In this series, we're giving you a break from the politicians and we're going to try to figure out the truth. Bracing concept, isn't it? We'll be looking at some of the big questions - immigration, lawmaking, regulations and trade. But in this first program, Tim Harford tackles two very basic questions: how much would we save if we left the EU? And what would we lose if we did?

There is a black hole in our knowledge of women and girls around the world. Campaigners say that they are often missing from official statistics and areas of their lives are ignored completely - but what needs to be done?

Producer: Charlotte McDonald Presenter: Tim Harford

The news aggregation website Zimbabwe Today recently ran a headline stating that 74% of African girls aged 15-24 are HIV positive. Although the statistic is not true, Mary Mahy from UNAIDS reveals that young women do have a higher infection rate than young men. Kyle Evans is a folk singing mathematician by trade who is always looking for new ways to communicate his love of maths to a sometimes apprehensive audience. Next week he is representing the UK against 26 other countries at the Cheltenham Science festival in England. He came into the studio to perform his competition entry.

Producer: Laura Gray Presenter: Ruth Alexander

What is the average length of stay in a refugee camp? It is regularly reported that it is 17 years but is this true?

Floppy Disks

This week’s shocking revelation of the computer world was that the Department of Defence still uses 1970s floppy disks to coordinate its nuclear weapons systems. But can it possibly be true that you could fit more than three million of them on a single ten dollar USB drive?

Producer: Laura Gray Presenter: Ruth Alexander

Recently one of our listeners contacted us to say he heard a BBC correspondent describe the iPhone as the most profitable product in history. It was just an off-the-cuff comment but it got us thinking - could it be true? We compare and contrast a range of products suggested by More or Less listeners to work out if the iPhone truly is the most profitable.

Producer: Laura Gray

Is London the most diverse city in the world? The new London mayor Sadiq Khan has claimed that it is, but is he right? How is diversity measured?

This month, British mathematician Sir Andrew Wiles will go to Oslo to collect the Abel prize, a prestigious maths prize for his work proving Fermat’s last theorem. Science author Simon Singh explains his work.

Producers: Laura Gray and Ed Davey.

At the beginning of the season of the English football Premier League, few people would have been brave enough to predict that Leicester City would finish top. But was it that surprising?

Tim Harford speaks to Lord Finkelstein, a political journalist, who has been running his own statistical model to assess the teams in the Premier League. We also hear from James Yorke from the football analytics website Stats Bomb. Was Leicester’s success down to the team’s skills, or was it down to luck?

Recently one of our listeners contacted us to say he heard a BBC correspondent describe the iPhone as the most profitable product in history. It was just an off-the-cuff comment but it got us thinking – could it be true? We asked listeners to get in touch with their suggestions. We take a look at a handful of them, from Viagra to popcorn in our quest for an answer. Could it be something more historical?

EU and trade: We take a look at the numbers on trade and at the UK’s relationship with the EU. Tim Harford interviews Chad P. Bown, a Senior Fellow at the Peterson Institute for International Economics.

Leicester City's Premier League success: At the beginning of the football season we explored the fallibility of predictions from experts and fans. As the season is ending, that is the only prediction we made correctly – that they are usually very wrong. Leicester City has had an astonishing success in winning the English Premier League. We take a look at the numbers behind the team’s performance.

Sexist Data Crisis: Are countries around the world failing to collect adequate details about their female citizens? Campaigners have argued we are missing data in areas that would help us understand women’s lives better, for example land and inheritance rights. We also explore how women’s work can be overlooked from labour surveys.

A Dutch statistician recently became suspicious by headlines in the Dutch news that women were being discriminated against when it came to getting science research funding. Professor Casper Albers of the Heymans Institute for Psychological Research, Groningen, discovered that the study into the funding process showed that when you looked at the overall numbers of successful candidates, women seemed to be less successful than men. And yet, when you looked at a breakdown of the different subjects people could apply for, it showed that women were not losing out disproportionately to men. How could two opposite findings be true? This contradiction is explained by a famous statistical paradox. We explain what is known as Simpson’s Paradox with the aid of a choir metaphor, performed by the BBC Singers.

How many people have come from the EU to live in the UK? And what impact do they have on the economy? This week it was reported there had been an increase in fire deaths – we aren’t so sure. We explain the achievement of Abel Prize winning mathematician Sir Andrew Wiles for Fermat’s Last Theorem. Plus, we explore the numbers behind Simpson’s Paradox.

What is the most expensive “object” ever built? There are plans in the UK to build a brand new nuclear power station called Hinckley Point. The environmental charity Greenpeace have claimed it is set to be the most expensive object on Earth. But could it really cost more to build than the Great Pyramid of Giza? We take a look at some of the most costly building projects on the planet.

EU Treasury report

This week there was much debate over the Treasury report which modelled how leaving the EU would affect the economy. Tim Harford speaks to the Spectator’s Fraser Nelson about how the document was presented to the public, and how it was reported. Chris Giles of the Financial Times explains that there are useful points to take from the Treasury’s analysis.

Hinckley Point nuclear power station

What is the most expensive “object” ever built? The environmental charity Greenpeace has claimed it is set to be the most expensive object on Earth. But could it really cost more to build than the Great Pyramids? We take a look at some of the most costly building projects on the planet.

Chances of serving on a jury

A listener in Scotland is curious to know what the chances are of being selected for jury service. Several of his family members have received summons, but he has not. We look at who is eligible to serve, and what your odds are of receiving a summons.

European Girls Maths Olympiad

Last week we told the story of how the European Girls Maths Olympiad (EGMO) came into being. We followed the UK team on their recent journey to Romania to compete against 38 other teams from Europe and around the world.

Life expectancy of a Pope

In 2014 Pope Francis alluded to the fact he didn’t expect to live more than another two or three years. A group of statisticians have taken a look at the life expectancy of popes over the centuries and decided that he may have been rather pessimistic.

Presenter: Tim Harford Producer: Charlotte McDonald

Life expectancy of a Pope

In 2014 Pope Francis alluded to the fact he didn’t expect to live more than another two or three years. A group of statisticians have taken a look at the life expectancy of popes over the centuries and decided that he may have been rather pessimistic.

The curse of the London Olympics

In a similar vein, is there an unusually high death count among athletes who took part in the London Olympics in 2012? The French press seem to think there is. Currently news reports estimate that 18 people have so far died since taking part in the sports event. The athletes come from teams around the world and have died from all sorts of causes – from cancer to drowning, murder, suicide, a helicopter crash among other things. But is there really a link between taking part in the London Olympics and the chances of dying? Or is it to be expected, statistically speaking, that 18 people have died over the last four years?

Celebrity deaths

A number of people have asked the team if more famous people have died this year compared to other years. It’s a hard one to measure – but we have had a go at some back of the envelope calculations with data from Who’s Who and BBC obituaries. Is the intuitive feeling that more people have died this year misplaced?

‘What British Muslims really think’ poll

This week many news outlets covered polling research carried out for a documentary on Channel 4. Some of the points that came out included that half of all British Muslims think homosexuality should be illegal and that 23% want Sharia Law. But how representative are these views? We speak to Anthony Wells from the blog UK Polling Report who explains the difficulties of carrying out polling.

The number of Brits abroad

Figures released this week suggested that there was an increase in the number of people coming to the UK from other parts of Europe. But many listeners have been asking – how many Brits are living in other parts of Europe? We try to find the best figures available.

European Girls Maths Olympiad

In 2012 a new international maths competition was started at the University of Cambridge. It was a chance for female students to get a chance of meeting girls from other countries and try to solve hard maths problems, as they are under represented at most other international competitions. We hear about how the competition got started in celebration of this year's competition in Romania.

Presenter: Tim Harford Producer: Charlotte McDonald

In the 1600s astronomers were coming up with measurements to help sailors read their maps with a compass. But with all the observations of the skies they were making, how do they choose the best number? We tell the story of how astronomers started to find the average from a group of numbers. By the 1800s, one Belgian astronomer began to apply this to all sorts of social and national statistics – and the ‘Average Man’ was born.