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

Headlines have claimed that “healthy life expectancy” in the UK has fallen by two years. What does this actually mean?

A new government report estimates that HS2 will cost almost double its original estimate. We ask where the money’s gone.

Chancellor Rachel Reeves has reduced VAT on theme parks, aquariums and other summer fun. But will these savings get passed on to the consumer?

And Tim gives a much-anticipated update on his recent marathon.

Contributors: Stuart McDonald - actuary at LCP Health Analytics John Burn-Murdoch - Chief Data Reporter for the Financial Times Kate Lamble - journalist and presenter of ‘Derailed: The story of HS2’ Dan Neidle - founder of Tax Policy Associates

Credits: Presenter: Tim Harford Reporter / Producer: Lizzy McNeill Producers: Tom Colls, Nathan Gower and John McMinn Production co-ordinator: Brenda Brown Sound mix: Neil Churchill Editor: Richard Vadon

What does it mean if you say that something is an epidemic? In the case of a virus, it usually means that it is spreading rapidly and that more and more people are getting infected.

When a disease isn’t on the rise but is there in a population at a reasonably steady level, we tend to say that the disease is endemic. But what if the thing you’re talking about is not a virus, but a feeling?

In 2023, the US surgeon general launched a report called “Our Epidemic of Loneliness and Isolation”, warning of the health harms of being lonely and socially isolated.

The idea that there is an epidemic of loneliness didn’t start there - the term was already in use in the US in the 2010s. And it’s a phrase that’s still going strong, popping up in news stories on a regular basis.

After that warning from the US Surgeon General, the World Health Organisation launched the Commission on Social Connection, with their director general warning that “more and more people are finding themselves isolated and lonely.”

But is it true that loneliness rates are increasing? Is it right to say we’re in the midst of an epidemic of loneliness? It’s hard to find the data that backs up this claim.

If you’ve seen a number in the news you think we should take a look at, email [email protected]

CONTRIBUTOR:

Professor Melody Ding, an epidemiologist and population behavioural scientist at the University of Sydney

This programme has been edited to correct a minor technical production error on 27/05/2026

CREDITS:

Presenter: Tim Harford Reporter: Tom Colls Production co-ordinator: Brenda Brown Sound mix: Dave O’Neill Editor: Richard Vadon

Tim Harford investigates some of the numbers in the news. On the programme:

Last week, Annunziata Rees-Mogg took to X to post a claim about the proportion of sex offences in Dorset that are committed by asylum seekers, writing that “asylum seekers make up 0.8% of Dorset’s population and 44% of alleged sex offenses. So unbelievable I had to check.” We checked too, and the number isn’t right.

In the last series of More or Less we suggested that nuclear power plant Hinkley C was spending so much on protecting the fish population that it would cost something like £250,000 per fish saved. We’ve had to take a look at that one too.

Last year, we looked at a report by the Bible Society based on polling from YouGov. The Quiet Revival suggested that churchgoing was on the rise in the UK, with young men leading the trend. YouGov now have an update on that survey.

How many caterpillars does a blue tit chick eat before it leaves the nest? In a recent nature documentary, Sir David Attenborough said the right number was 20,000. We’re not so sure.

If you’ve seen a number in the news you think we should take a look at, email the more or Less team: [email protected]

CONTRIBUTORS:

Madeleine Sumption, Director of the Migration Observatory at Oxford University Professor David Voas, Emeritus Professor of Social Science in the UCL Social Research Institute Annette Jäckle, Professor of Survey Methodology at the University of Essex and a Deputy Director of the UK Household Longitudinal Study Dr Malcolm Burgess, Principal Conservation Scientist at the RSPB

CREDITS Presenter: Tim Harford Reporter: Lizzy McNeill Producer: Nathan Gower and Josh McGinn Series producer: Tom Colls Production co-ordinator: Brenda Brown Sound mix: James Beard Editor: Richard Vadon

It’s said that AI could soon be coming for the jobs of artists, lawyers, and software engineers. But it might now also be threatening a role at the height of academia – are pure mathematicians safe? Last month, a Stanford mathematician woke up to an email, claiming to have the solution to a problem he'd been working on for seven years - a 60-year-old conundrum known as "Erdos Problem 1196". The answer had been generated in just 80 minutes - by ChatGPT. Since the end of last year, AI has been providing solutions to a number of novel maths problems, but Problem 1196 is the first to raise eyebrows within the mathematical community. In this episode, we talk to the mathematicians who've worked on Problem 1196 and find out what the rise of AI could mean for the future of their field. CONTRIBUTORS: Katie Steckles, Mathematician and communicator Jared Duker Lichtman, Szegő Assistant Professor of Mathematics at Stanford University Liam Price, amateur mathematician Credits:

Presenter: Charlotte McDonald Producer: Josh McMinn Series producer: Tom Colls Production co-ordinator: Brenda Brown Sound mix: Dave O'Neill Editor: Richard Vadon

According to the World Health organisation, smoking kills some 7 million people every year. It is one of the world’s leading causes of preventable death.

Because smoking causes lung cancer and other awful health conditions, many smokers switch to vaping - using nicotine-based e-cigarettes.

But the World Health organisation is also concerned about vaping. Last year they said 100 million people around the world are now using e-cigarettes, including millions of children, and warned that they were fuelling a new wave of nicotine addiction.

But how do the health risks of these two means of getting nicotine into your bloodstream compare?

According to a recent headline in the Daily Mail, they’re basically the same. Here’s the headline:

“Vaping is linked to lung and mouth cancer in major study, as experts warn: 'It is NOT safer than smoking’”

But is vaping really just as bad for you as smoking?

CONTRIBUTOR:

Professor Lion Shahab, Co-Director of the UCL Tobacco and Alcohol Research Group

CREDITS:

Presenter: Charlotte McDonald Reporter/producer: Tom Colls Production co-ordinator: Brenda Brown Sound mix: Dave O’Neil Editor: Richard Vadon

If you spend much time on social media, and we don’t necessarily recommend it, then you’ve probably come across a strange fascination with water consumption.

Mainly, this is people telling you that using AI is terrible for the planet because of how much water it uses. We’ve already made a couple of programmes about the numbers in those arguments and, long story short, they probably aren’t saying what you think they’re saying.

But on platforms like X, BlueSky, and TikTok, an opportunity to keep an argument going is rarely missed And one of the numbers that’s been enlisted in that glorious cause concerns the water that’s used for a seemingly unrelated past-time - eating beef. Here’s an example from a user on X:

“A kilogram of beef requires over 15,000 litres of water to produce,” they wrote. “A vegan who uses ChatGPT every day is living a more sustainable lifestyle than someone who regularly eats beef while boycotting AI.”

Ignoring the AI part, is that true? Does it actually take 15,000 litres of water to produce a kilogram of beef? It turns out that the number isn’t wrong, but it probably isn’t saying what you think it’s saying.

If you’ve seen a number you think we should take a look at, email the More or Less team: [email protected]

CONTRIBUTORS: Mesfin Mekonnen, Assistant Professor at the University of Alabama Mark Mulligan, Professor of Physical and Environmental Geography at King's College London Tim Hess, Professor of Water and Food Systems at Cranfield University CREDITS: Presenter: Charlotte McDonald Producer: Mhairi MacKenzie Series producer: Tom Colls Production co-ordinator: Brenda Brown Sound mix: Emma Harth Editor: Richard Vadon

Vaccine policy in the US is something of an ideological battleground.

Health Secretary Robert F Kennedy Jr is a vaccine sceptic, and since taking office he has attempted to remake US vaccine policy.

In March a judge blocked his proposal to cut the number of jabs that are recommended for kids.

At the same time, last year saw the worst measles outbreak in the US in decades. There were more than 2000 cases last year, and three people died. There have been more than 1500 cases so far in 2026.

There’s a lot going on, so it’s possible the public’s views on vaccination are shifting.

A new poll published by online news site Politico added a big claim into the mix. According to the headline “more Americans doubt vaccine safety than trust it”.

But is that what the survey actually found?

Dr David Higgins, a paediatrician and public health assistant professor who writes a Substack called Community Immunity, explains why he believes the headline is misleading.

If you've seen a number in the news you think we should take a look at, email [email protected]

Presenter: Charlotte McDonald Series producer: Tom Colls Production co-ordinator: Brenda Brown Sound mix: Neil Churchill Editor: Richard Vadon

US president Donald Trump is no fan of wind turbines, or windmills as he calls them.

Not only does he think they ruin the view from a golf course he owns in Scotland, but they are also deadly to birds.

“If you love birds, you’d never want to walk under a windmill,” he said in 2019.

“It’s a very sad, sad sight. It’s like a cemetery. We put a little statue for the poor birds.”

Earlier this year he posted on Truth Social saying that wind turbines were killing “millions” of birds.

But is that true? We speak to Dr Hannah Ritchie, Deputy Editor at Our World in Data and senior researcher at the University of Oxford, who has dug into the numbers on bird mortality and wind turbines.

Credits:

Presenter: Charlotte McDonald Producer: Mhairi MacKenzie Series producer: Tom Colls Production co-ordinator: Brenda Brown Sound mix: Sue Maillot Editor: Richard Vadon

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: [email protected]

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 [email protected]

Presenter: Charlotte McDonald Producer / Reporter: Nathan Gower Series Producer: Tom Colls Programme Coordinator: Brenda Brown Sound Mix: Dave O’Neil Editor: Richard Vadon