More or Less: Behind the Stats

Sometimes it is obvious to everyone when an idea is harmful, or a piece of advice is damaging. But not always. Occasionally bad ideas and terrible advice end up being accepted in society and supported by people in authority. In such circumstances, one of the most powerful tools for changing people's minds is evidence – scientific studies that show beyond doubt that the bad idea is, indeed, a bad idea. That's the subject of a new book by Helen Pearson, titled Beyond Belief: How Evidence Shows What Really Works. An editor at the scientific journal Nature in her day job, the book chronicles those determined individuals who shake up the status quo by gathering just the right kind of evidence. One story in that book stood out to us on More or Less as it shows just what happens when you don't have the evidence you need to challenge a dangerous way of doing things. It's the story of a piece of advice from childcare expert Dr Benjamin Spock. In a 1958 revision of his bestselling parenting guide Baby and Childcare he made a small change to his advice on sleeping position – advising parents to put their babies to sleep on their front. It eventually became clear that this sleeping position was associated with a significant increase in the risk of sudden infant death, or cot death. CREDITS: Presenter: Charlotte McDonald Series producer: Tom Colls Production co-ordinator: Brenda Brown Sound mix: Rod Farquhar Editor: Richard Vadon

When you’re listening to the news, you will often hear words that are meant to communicate the probability of something happening. A terrorist attack is “a realistic possibility”, the spread of a certain strain of virus is “highly likely", the relegation of your favourite football team is “possible”. But when you hear these terms, do you really know what kind of probabilities they’re trying to convey? Do you know how likely “likely” is? Or what probability “probable” is meant to get across? In some cases, it seems you probably don't. Professor Adam Kucharski, author of Proof, the Uncertain Science of Certainty, designed a quiz to work out the actual probabilities of the language we use to convey risks. The data he got back shows how sometimes these words mean very different things to different people. If you want to try the quiz for yourself, head over to https://probability.kucharski.io/ Email the More or Less team: moreorless@bbc.co.uk CREDITS: Presenter: Charlotte McDonald Series producer: Tom Colls Production co-ordinator: Brenda Brown Sound mix: Gareth Jones Editor: Richard Vadon

As Artificial Intelligence continues to expand rapidly, some people have raised concerns about its potential environmental impact - in particular its use of water, which is used to cool both data centres and the power generators that supply them with electricity. One recent book on AI contained the alarming prediction that AI could consume between 4 and 6 trillion litres a year by 2027. Could this eye-popping figure be right? If not, what is the correct figure, and is it a big number? The devil, as ever, is in the detail, and with the help of expert Alex de Vries-Gao, the More or Loss team has taken a deep dive to get to the truth about AI and water consumption. If you’ve seen a number in the news and you think More or Less should take a look, email the team on moreorless@bbc.co.uk Presenter: Charlotte McDonald Producer / Reporter: Nathan Gower Series Producer: Tom Colls Programme Coordinator: Brenda Brown Sound Mix: Dave O’Neil Editor: Richard Vadon

Paul Ehrlich’s bestselling book The Population Bomb opens with an apocalyptic paragraph. “The battle to feed all of humanity is over,” it states. “In the 1970s and 1980s hundreds of millions of people will starve to death in spite of any crash programs embarked upon now. At this late date nothing can prevent a substantial increase in the world death rate.” Professor Ehrlich, who died last week, made a simple argument. The global population was outrunning our capacity to produce enough food to feed everyone. Famine, disease and nuclear Armageddon would follow if the population was not controlled. The book made him a celebrity, and he regularly spoke in public, warning of the imminent threat to humanity. Sometimes his warnings were quite vague in terms of the timescale, but other times not - he was reported as saying in 1968 that if current trends continued, by the year 2000, the UK would be a “small group of impoverished islands, inhabited by some 70 million hungry people". "If I were a gambler," he was quoted as saying, "I would take even money that England will not exist in the year 2000". But the UK did not collapse, the global death rate did not increase, and we have more food per person now than when he wrote the book. So, what went wrong with Paul Ehrlich's predictions of a population apocalypse? If you’ve seen a number or claim that you think More or Less should look at, email moreorless@bbc.co.uk CONTRIBUTORS Vincent Geloso, Assistant Professor of economics at George Mason University Darrell Bricker, global CEO of Ipsos Public Affairs and co-author of Empty Planet, the Shock of Global Population Decline Peter Alexander, Professor of Global Food Systems at the University of Edinburgh CREDITS: Presenter: Charlotte McDonald Series producer: Tom Colls Production co-ordinator: Brenda Brown Sound mix: Dave O’Neil Editor: Richard Vadon

In most sports, men compete against men and women compete against women. That is generally considered fair, because men are faster, more powerful and have greater endurance. But there is an ongoing controversy about transgender women - people who were born male and now identify as women. Is it fair for them to compete in the women’s sport category or do they have an advantage? A study in the British Journal of Sports Medicine recently added to the debate with an analysis that found the strength and fitness of transgender women is “comparable” with that of women. More or Less looks into the research to explain what it does, and does not, say. Contributors: Professor Alun Williams, Manchester Metropolitan University Credits: Presenter: Charlotte McDonald Reporter: Tom Colls Production co-ordinator: Brenda Brown Sound Mix: Gareth Jones Editor: Richard Vadon

On Saturday 28th February, the US and Israel launched a military attack on Iran, targeting the country's missile infrastructure, military sites and leadership. In response, Iran launched a wave of strikes across the region, including on Israel and the Gulf states. Iran has a stockpile of ballistic missiles, which it’s firing at neighbouring countries. These countries in turn are using interceptor missiles to try and shoot them down. But is it clear who will run out of missiles first? Contributor: Kelly Grieco, senior fellow at the Stimson Center Credits: Presenter: Charlotte McDonald Series producer: Tom Colls Production co-ordinator: Brenda Brown Sound Mix: Tom Brignell Editor: Richard Vadon

Have a million new species just been discovered? That’s the claim made by Dr Oliver Vince, co-founder of a company called Basecamp Research, who are collecting genetic data to train AI systems. The hope is that they’ll be able to use this to discover new medicines. But is this number a good one? Rob Finn, from the European Bioinformatics Institute, explains what is being counted and how you go about counting them. Credits: Presenter and producer: Tom Colls Production co-ordinator: Brenda Brown Sound mix: Dave O’Neill Editor: Richard Vadon

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

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

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

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

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

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

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

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

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

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

What kind of state does the UK find itself in as we start 2026? That’s the question Tim Harford and the More or Less team is trying to answer in a series of five special programmes. In the final episode, we’re looking at the numbers behind some of the UK’s most potent political debates: Has 98% of the UK’s population growth come from immigration? Do we spend more on benefits in the UK than in other high-income countries? Is the gap between rich and poor growing? Get in touch if you’ve seen a number in the news you think we should take a look at: moreorless@bbc.co.uk Contributors: Madeleine Sumption, Director of the Migration Observatory at Oxford University Lukas Lehner, Assistant Professor at the University of Edinburgh Arun Advani, Director of the Centre for the Analysis of Taxation and a Professor of Economics at the University of Warwick. Alex Scholes, Research Director at NatCen Credits: Presenter: Tim Harford Producers: Lizzy McNeill, Nathan Gower, Katie Solleveld and Charlotte McDonald Series producer: Tom Colls Production co-ordinator: Maria Ogundele Sound mix: Sarah Hockley and James Beard Editor: Richard Vadon

What kind of state does the UK find itself in as we start 2026? That’s the question Tim Harford and the More or Less team is trying to answer in a series of five special programmes. In the fourth episode, we’re searching for answers to these questions: Are one in four pensioners millionaires? Is England’s education system performing better than Finland’s? And how does it compare to Scotland, Wales and Northern Ireland Are our prisons going to run out of space? Is the weather getting weirder? Get in touch if you’ve seen a number in the news you think we should take a look at: moreorless@bbc.co.uk Contributors: Heidi Karjalainen, Senior Research Economist at the Institute for Fiscal Studies Harry Fletcher-Wood, Director of Training at StepLab John Jerrim, Professor of Education and Social Statistics at University College London Cassia Rowland, Senior Researcher at the Institute for Government Friederike Otto, Professor of Climate Science at Imperial College London Credits: Presenter: Tim Harford Producers: Lizzy McNeill, Nathan Gower, Katie Solleveld and Charlotte McDonald Series producer: Tom Colls Production co-ordinator: Maria Ogundele Sound mix: Sarah Hockley and Neil Churchill Editor: Richard Vadon

What kind of state does the UK find itself in as we start 2026? That’s the question Tim Harford and the More or Less team is trying to answer in a series of five special programmes. In the third episode, we’re searching for answers to these questions: Are there really 700,000 empty homes that could be used to solve the housing crisis? Does the NHS pay less for drugs than health services in other countries? Is violent crime going up or down? Is the UK in the midst of a fertility crisis? Get in touch if you’ve seen a number in the news you think we should take a look at: moreorless@bbc.co.uk Contributors: Dr Huseyin Naci, Associate Professor and Director the Pharmaceutical Policy Lab at the London School of Economics Professor Jennifer Dowd, deputy director of the Leverhulme Centre for Demographic Science at the University of Oxford Credits: Presenter: Tim Harford Reporters: Lizzy McNeill and Nathan Gower Producers: Katie Solleveld and Charlotte McDonald Series producer: Tom Colls Production co-ordinator: Maria Ogundele Sound mix: Sarah Hockley and James Beard Editor: Richard Vadon