More or Less: Behind the Stats

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.

Epidemiologist Adam Kucharski discusses how the Neknomination craze mirrors an infectious disease outbreak and will eventually fade out. The podcast also delves into global income tax rates, comparing which countries tax the wealthy and average workers the most and the least.

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.