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BBC Radio 4

Tim Harford explains - and sometimes debunks - the numbers and statistics used in political debate, the news and everyday life

More or Less: Behind the Stats

AI can make mistakes – and AI chatbots like ChatGPT warn you about that whenever you ask them anything.

These mistakes sometimes involve making up entirely fictitious, factually false statements known as “hallucinations”.

Whether these hallucinations matter depends on what you’re using AI for, and whether they are spotted and corrected.

The team on More or Less were slightly surprised to read a headline in Fortune magazine, claiming that a top academic AI conference accepted research papers which contained 100 AI-hallucinated citations.

You might think that the top AI researchers in the world would be careful about using AI to write their research papers.

Alex Tui, CTO and co-founder of GPTZero – whose company discovered the hallucinations – explains what’s going on.

CREDITS:
Presenter and producer: Tom Colls
Sound mix: James Beard
Production co-ordinator: Brenda Brown
Editor: Richard Vadon

Did AI researchers let AI hallucinations into scientific papers?

Modern sport can seem awash with money, but it’s been claimed that the richest sportsperson of all is an ancient Roman Charioteer from the second century AD called Gaius Appuleius Diocles, with career winnings that stood at 35 million sesterces. One calculation has translated that into an astonishing $15 billion dollars today, and it’s a figure that’s stuck. But should we believe it?
 
Duncan Weldon talks to ancient historian Professor Mary Beard from the University of Cambridge to learn more about the big business of chariot racing, and how we should think about money and wealth in the economies of the past.
 
Presenter: Duncan Weldon
Producer: Nathan Gower
Series Producer: Tom Colls
Editor: Richard Vadon
Programme Coordinator: Brenda Brown 
Sound Engineer: James Beard

Is an ancient charioteer the best paid sportsperson of all time?

Chelsea striker Liam Delap has recently stunned fans on Instagram by apparently doing incredibly complicated calculations in his head, finding what’s known as the cube root of some very large numbers.

But is he really a human calculator? Or is there something else going on? Tim Harford speaks to Rob Eastaway, mathematician and author of ‘Maths on the Back of an Envelope’ to learn about the trick you can use to pull this off - and while he’s here we also ask him about the trend of more goals being scored in the Premier League.

Presenter: Tim Harford
Producers: Nathan Gower
Series Producer: Tom Colls
Editor: Richard Vadon
Programme Coordinator: Brenda Brown 
Sound Engineer: James Beard
Credit: Video of Liam Delap from Chelsea’s Instagram account, chelseafc

Is this Premier League striker a secret maths genius?

Could European Nato members use their large holdings of US shares and bonds to put pressure on America? It’s a question that some in Europe found themselves asking as the geopolitical crisis over Greenland escalated and leaders desperately tried to think of ways to dissuade Donald Trump. 
 
It is true that trillions of dollars of American financial assets are held in Europe. But the devil, as ever, is in the detail. 
 
Tim Harford talks to Toby Nangle, a journalist with the Financial Times, to drill down into the numbers.

Presenter: Tim Harford
Producer: Nathan Gower
Series Producer: Tom Colls
Editor: Richard Vadon
Programme Coordinator: Brenda Brown 
Sound Engineer: James Beard

Could Europe use its financial muscle to strong-arm the US?

Tim Harford investigates some of the numbers in the news. This week:

Is it true that someone needs to earn £71,000 before they receive more money than a family on benefits?

Did Canadian prime minister Mark Carney get the GDP of Canada and the Nordic countries wrong?

Are 1990s pop icons Right Said Fred right about what they said about church attacks?

Is a sauna really ten times as hot as Wales in the winter?

And Tim hits the science lab treadmill to find out if he can run a four-hour marathon.

If you’ve seen a number in the news you want the team on More or Less to have a look at, email moreorless@bbc.co.uk

Contributors:
Gareth Morgan, benefits expert and author of the Benefits in the Future blog
Joe Shalam, policy director of the Centre for Social Justice
Professor Kelly Morrison, head of physics at Loughborough University
Dr Danny Muniz, a senior lecturer in Exercise Physiology at the University of Hertfordshire

Credits:
Presenter: Tim Harford
Reporters: Nathan Gower, Lizzy McNeill and Tom Colls
Production co-ordinator: Brenda Brown
Sound mix: Gareth Jones and James Beard
Editor: Richard Vadon

Can you get £71,000 on benefits?

The vast island of Greenland has found itself at the centre of a geopolitical crisis. But a little bit of geography can help us see the situation in a new light.

YouTuber and map expert Jay Foreman explains how Mercator maps - the maps that the vast majority of us use to understand the world - contain necessary but massive distortions and hugely exaggerate the size of the Arctic island. 

So, why is making a flat map of a round globe so difficult? Why did we end up with a problematic map in the first place? And are there any alternatives?

Presenter: Tim Harford
Producer: Nathan Gower
Series Producer: Tom Colls
Editor: Richard Vadon
Programme Coordinator: Brenda Brown 
Sound Engineer: James Beard

Is Greenland as big as Africa?

Tim Harford investigates some of the numbers in the news. This week: 

How far away is Greenland from the United States? We check a number From Our Own Correspondent. 

Does converting our entire energy system to be carbon neutral come with a £7.6 trillion price tag?

Is the inevitable rise of house prices in the UK not so inevitable after all? 

Can the great mathematicians of history answer the question of the hour: how to play The Traitors? 

If you’ve seen a number in the news you want the team on More or Less to have a look at, email moreorless@bbc.co.uk

Contributors: 
Jay Foreman, one half of YouTube duo the Map Men 
Mike Thompson, chief economist of the National Energy System Operator 
David Turver, author of The Cost of Net Zero, a report from the Institute of Economic Affairs 
Neal Hudson, housing market analyst and founder housing research website BuiltPlace 
Dr Kat Phillips, mathematician and Innovation research associate at the University of Warwick, Traitors aficionado 

Credits: 
Presenter: Tim Harford 
Reporter: Tom Colls 
Producers: Nathan Gower and Lizzy McNeill 
Production co-ordinator: Brenda Brown 
Sound mix: James Beard 
Editor: Richard Vadon

How close is Greenland to the United States?

In Autumn 2025 a paper in South Korea was published that excited many a vaccine sceptic online. The paper claimed that receiving a vaccination against Covid19 was linked to a 27% increase in cancer risk. 

However, when you dig into the data there is no evidence that the vaccine caused the cancer. We spoke to Professor Justin Fendos to explain why we cannot take this type of statistical analysis at face value. 

Presenter: Tim Harford
Producer: Lizzy McNeill
Series Producer: Tom Colls
Editor: Richard Vadon
Production Coordinator: Brenda Brown
Sound Mix: James Beard

No, a study has not shown that the covid jab causes cancer

Tim Harford investigates some of the numbers in the news. This week: A headline in the Mail says more than 100 private schools have closed since Labour came to power and ended the VAT exemption for private schools. Is that number right? 

Is it true that when Covid hit the UK, a one-week delay in imposing lockdown led to 23,000 deaths? 

Do 10 million families rely on X as their main source of news? That’s what government spokesperson Baroness Ruth Anderson said in the House of Lords, but is it correct? 

s there really a “quiet revival” of Christian worship? Two YouGov polls found churchgoing had gone up by 50% between 2018 and 2024 in England and Wales. New polling data suggests otherwise. 

If you’ve seen a number in the news you want the team on More or Less to have a look at, email moreorless@bbc.co.uk 

Contributors: 
Professor Sir David Spiegelhalter, Emeritus Professor of Statistics in the Statistical Laboratory, University of Cambridge 
Professor Sir John Curtice, Senior Research Fellow at the National Centre for Social Research 

Credits: 
Presenter: Tim Harford 
Reporters: Tom Colls and Nathan Gower 
Producers: Charlotte McDonald and Lizzy McNeill 
Production co-ordinator: Brenda Brown 
Sound mix: Gareth Jones Editor: Richard Vadon

Have more than 100 private schools been forced to close because of VAT?

When people think of oil rich nations their mind generally goes to Saudi Arabia, Iraq and the US. 

But according to international statistics, the country with the largest oil reserves is Venezuela, with 300 billion barrels worth. 

At their peak they produced over 3.5 million barrels of the stuff per day. However, due to lack of investment, sanctions and mismanagement that peak is long gone. 

Following their military intervention, the US administration claims they can get Venezuela's oil production up and running at full capacity within 18 months.

But can they, and why is it that estimates for other countries oil reserves have fluctuated but Venezuela’s has stayed at 300 billion barrels for over two decades? 

Presenter: Tim Harford
Producer: Lizzy McNeill
Series Producer: Tom Colls
Editor: Richard Vadon
Production Co-Ordinator: Brenda Brown
Sound Mix: Dave O’Neill

Does Venezuela really have the biggest oil reserves in the world?

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.

WS More or Less: Wedding gift economics

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