More or Less: Behind the Stats

Nigeria's bureau of statistics has overhauled the way it calculates the country's GDP figures. With GDP now estimated at around $510 billion, it has surpassed South Africa as the continent's largest economy. But just because it has earned this accolade – does that make it one of the richest? Plus was the President of the World Bank, Jim Yong Kim, right to say recently that Nigeria is one of just five countries that together are home to two-thirds of the world’s extreme poor? We sift through the statistics to find out if economic development is benefitting everyone in Nigeria. This programme was first broadcast on the BBC World Service.

How many people in the world live in freedom? The BBC's Freedom 2014 season got Tim Harford and the More or Less team wondering about this. It's actually pretty hard to put a number on freedom, so Tim begins by looking at something more quantifiable: how many people live in a democracy? And are people in democracies happier? Tim Harford looks at the numbers with Simon Baptist from the Economist Intelligence Unit. Plus, he examines the price of a cup of coffee, and whether Ruth Alexander can be persuaded to pay for his. This programme was first broadcast live on the BBC World Service on 01 April 2014 from the Media Café at BBC New Broadcasting House in London.

Are there really be 300,000 French people in London and would they really want to leave France for the UK anyway? The Mayor of London, British journalists and commentators have trotted out this "fact" a number of times over the last few years to illustrate just how popular the UK’s capital is with its neighbours across the Channel. It appears that Nicolas Sarkozy may have said it as far back as 2008. Wesley Stephenson and Charlotte McDonald brush off their best French to find out the truth. This programme was first broadcast on the BBC World Service.

Could Bayesian statistics find Flight MH370 from Kuala Lumpur to Beijing? This niche form of statistical modelling has been used to find everything from submarines to missing people. More or Less explores how it was used to locate the wreckage of Air France flight 447 from Brazil to France which disappeared in 2009. This programme was first broadcast on the BBC World Service.

Your questions answered - Do the Maasai in Africa number one million? Is it true that a quarter of Americans do not know the Earth goes round the sun? Are half of Tasmanians innumerate and illiterate? Plus, Do the 85 richest people in the world hold the same amount of wealth as the poorest half? This programme was first broadcast on the BBC World Service.

Are there 21 million slaves in the world today? Director of 12 Years a Slave, Steve McQueen, made this claim at both the Oscars and the BAFTAs while accepting awards. More or Less looks into the definition of a slave, where they can be found, and explores how they can be counted. This programme was first broadcast on the BBC World Service.

Becoming a pro on practice alone – is that possible? Or do you need innate talent? After reading books promoting the idea, a photographer with no natural talent explains how he is practising for 10,000, hours to become a professional golfer. We hear David Epstein, author of 'The Sports Gene', and Malcolm Gladwell, author of 'Outliers' explain their views on whether you need innate ability. This programme was first broadcast on the BBC World Service.

The rise and fall of an online epidemic: How studying the spread of infectious diseases suggests the global drinking craze Neknomination will fizzle out. Drinkers post videos of their exploits and nominate others to do the same – but eventually the fad will run out of steam says epidemiologist Adam Kucharski from the London School of Hygiene and Tropical Medicine. Plus, while politicians debate how much to tax the rich in France and the UK– we look at which countries levy the highest and the lowest rates of income tax for both the wealthy and average worker. This programme was first broadcast on the BBC World Service.

Can economics help you find love? Tim Harford and the team look at the maths behind modern match-making. Economist Michele Belot from the University of Edinburgh explains why women are pickier than men at speed dating events. Plus - how analysing numbers from online dating agencies can help improve the chances of finding a partner: a personal story by Amy Webb, CEO of digital strategists Webbmedia Group. This programme was first broadcast on the BBC World Service.

In the US, more people are dying from drug overdoses than from road traffic accidents and firearms. As headlines are filled with the news that actor Philip Seymour Hoffman died from an overdose recently, the team takes a look at the number of deaths from drug overdoses of both illegal and prescription drugs in the US and the rest of the world. This programme was first broadcast on the BBC World Service.

How much do migrants cost or benefit a nation? Plus, planning a wedding - when you have friends and family all around the world and a finite number of places at the venue, how do you work out how many invitations to send? Tim Harford speaks to a couple who thought statistics might have the answer. This programme was first broadcast on the BBC World Service.

Chancellor George Osborne says a 50p tax rate does not bring in much revenue; Shadow Chancellor Ed Balls says it does. Tim Harford takes a look at why it is so hard to pin down how much tax is owed by the wealthy. Plus, have wages risen? How much does it cost to raise a child? Who do you invite to your wedding?

Do two large glasses of wine triple your risk of mouth cancer, as claimed on a health leaflet spotted by a sceptical listener? Tim Harford examines the difficulties of extracting smoking from the equation. Surprising as this may seem, one of the world's best tennis players of all time, Roger Federer, is also the worst ranked player on one scale. The scoring system makes it possible to lose a match despite winning more points, and Federer has lost the highest percentage of these types of games. Tim speaks to sports number-cruncher Ryan Rodenberg about why this might be the case. This programme was first broadcast on the BBC World Service.

What does a detailed look at immigration statistics tell us about the benefits, or otherwise, of welcoming overseas citizens? Plus, is it true that by the age of 60, more than twice as many women as men are single, and that older men are often living with younger men? Do two large glasses of wine triple your risk of mouth cancer? And which of the world's best tennis players of all time is also the worst-ranked player in one sense. Tim Harford presents.

An apple-a-day will actually keep the doctors away, according to a study in the Christmas edition of the British Medical Journal. It generated headlines around the world. But were the media right to take the story so seriously? Tim interviews one of the study’s authors and critic Paul Marantz. And, mathemagical mind-reading: Jolyon Jenkins reveals the maths behind a classic long-distance mind-reading card trick. Presenter: Tim Harford. Producer: Ruth Alexander. This programme was first broadcast on the BBC World Service.