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Is strenuous jogging bad for you?
00:27:42
Tim Harford on claims that keen runners might be damaging their health.
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A
Thank you for downloading this programme from BBC Radio 4. I'm Tim Harford. Hello and welcome to More or Less the balsamic vinegar on your statistical salad. This week, the cost of university tuition fees. And as the election begins to cast its long shadow, we ask whether there's really such a thing as a safe seat. But first, let's talk about jogging. A convenient way to keep fit or a steady plod towards the chill solitude of the grave. Because, as the BBC, rather unhelpful, helpfully reported this, too much jogging, as bad as no exercise at all, which doesn't tell us a lot. The clue is in the phrase too much. Too much of anything is excessive. That's not really a fact about jogging, but a fact about the English language. Anyway, soon messages came flooding in to more or lessbc.co.uk, some were sceptical and some rather worried.
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B
I feel very healthy and wonder how close to death am I really?
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Asked Manya, who regularly jogs more than two and a half hours a week at a pretty good pace. The BBC article was referring to a study published in the Journal of the American College of Cardiology. So we decided to turn to somebody who'd analyzed it.
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C
Hello.
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A
Dr. Alicia White of Bayesian, which is a consulting firm specialising in clinical evidence. She analysed the study on behalf of the National Health Service behind the Headlines website. I asked her what the researchers had done.
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C
They assessed whether people jogged and if they did jog, how much they jogged, how fast they jogged, how frequently they jogged. And then they also looked at a group of people who were essentially sedentary, who didn't do very much exercise at all, less than two hours a week of only very light exercise at most. And then it followed those people up over about 10 to 12 years to see who died with within that period. And then compared the different groups of people to see if they could find any differences in their risk of death over that period, specifically.
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A
And they were pooled into various groups. So the sedentary group and the light jogging, the moderate jogging, what was the definition of strenuous jogging?
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C
So, first of all, they split them according to essentially the quantity of jogging. So how many hours a week did they do? They also looked at the frequency of jogging. So how many times a week did they jog? And also jogging pace. So this is self defined jogging pace. Did they think they were slow, average or fast? And they analyzed each of those groups separately and compared them versus the sedentary group. So the light joggers tended to be the Ones who were jogging at a slow pace or to average pace less than two and a half hours a week and generally three times a week or fewer. And the strenuous joggers, they were the ones who tended to be jogging at a fast pace between two and a half and four hours over four hours a week and often very frequently. So usually above three times a week.
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A
And then we were told this notorious result, that too much jogging is bad for you. I just wanted to ask how many people in the strenuous jogger category actually died?
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C
Two.
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D
Two?
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C
Yes, two.
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A
That doesn't sound like a lot.
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C
No, it's not.
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A
And it could easily have been 1 or 3 or 0.
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C
Yes, it could have been. That's the issue really is that we can't say with such small numbers, we really can't say with any level of certainty whether that the proportion who died in that group is different to those in the sedentary group.
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A
So is this just a case of a study that didn't look at enough people or is it that just the number of people in that particular category of strenuous joggers wasn't big enough to form firm conclusions?
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C
I think it was a relatively large study, but yes, I would say that in the strenuous group, the number of people in there, so it was about 36 people when they looked at the people who had all of the data available, that it's not large enough for that group alone to be able to tell you with confidence about the effects on death in that group.
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A
And these two people, they could have died from anything. They could have choked on a pint of beer or fallen off a cliff or it could be anything at all.
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C
Yes. There's no information provided in the study about what these two people died from. And they themselves say that they can't analyze the effects on different causes of death. So this is just deaths from any cause at all.
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A
So would a more reasonable reading of this study be to say that people who engage in light exercise live longer than people who don't exercise. And we can't really say very much about people who engage in strenuous exercise because we didn't have enough of them in our study?
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C
Yes, I think that's reasonable. Essentially those who engaged in light jogging, and this is very specifically jogging, it didn't look at other forms of physical activity, did tend to be less likely to die of a follow up than those who didn't engage in exercise. So those who are sedentary, but yes, with strenuous jogging, I wouldn't be able to say with any confidence whether you were less or more likely to die or just the same as sedentary non joggers based on this study alone.
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A
Why do you think people got so excited about the study in the media?
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C
Well, it's difficult to say, but I think sometimes people get bored with a standard message, which is essentially what this is saying, which is, you know, doing some exercise is good for you instead of sort of focusing on that aspect of the study. I think maybe sometimes the oh, actually maybe lots of exercise is no good for you at all, is a different spin to put on it to make it a more interesting study than, what a surprise. Moderate exercise is good for you or light to moderate exercise is good for you.
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Alicia White, you're listening to more or less university tuition fees. Who's really paying them? Recent reports say that the Government's decision to almost triple the maximum that students can pay to £9,000 a year has saved taxpayers next to nothing. The Labour leader, Ed Miliband, is believed to be considering reducing fees from £9,000 to a maximum of £6,000 a year. But is it fair to call the current scheme expensive for taxpayers? And would Labour's plans save the government more money? I turned to BBC Newsnight's policy editor Chris Cook, who sat me down for a brief history of the university tuition fee.
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E
From the early 1960s, we started expanding the universities. The problem was that back then we gave students grants to live off and we paid their fees in full. And what this meant was that as the expansion continued apace, the cost of the system grew and grew. And the government solution for much of that time was simply to squeeze the amount per student that we gave out. But what that meant was that by the mid-90s, the universities were really being hammered and they couldn't really keep going like that. So in the late 90s, we introduced tuition fees. So students were asked to pay a contribution. Not the full cost, just a contribution towards their studies. That rose in the mid 2000s to about £3,000 a year. And then finally, under the coalition, it rose to £9,000 a year in 2012. So today, if you're an art student, for example, you probably pay the entire cost of your own tuition, although if you're a doctor, you still only pay a portion.
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A
So when the government is producing figures saying how much this scheme is going to cost, what drives those figures?
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E
Well, the three really important assumptions they have to make are, first of all, how rich are we now? And how rich are we going to be in the future. So that's wage growth. The second thing is, at what point will they start billing graduates for their student loans? So that's how generous do we want to be to them? The third thing is the cost of government borrowing, because remember that ultimately the student loan scheme is a policy which takes a lot of money from the markets and then lends it on to students. And if we can borrow money more cheaply from the markets, it makes the whole loan system much, much cheaper.
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So we've got those three factors. Are we doing a good job of estimating them?
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E
Well, the first one is kind of unknowable. That's the wage growth in future. We've all been taken by surprise recently by sluggish wage growth. That's actually one of the things that's been driving up our estimate for the cost of the loan scheme. The second one, the point at which we ask graduates to repay, is completely within the control of the government. And ultimately, if we really thought that the loan scheme was becoming much too expensive, we can control it because we can simply slow down the pace at which we raise it. At the moment, we assume we're going to raise it at about 4% a year in perpetuity. You could knock it down. You could knock it down. So it rose with prices and that would dramatically carve down the cost of the loan scheme. The third thing is the interest rate. So at the moment, the government assumes that it can borrow at around 3.8% a year when it's doing its maths on how much the loan scheme costs. In reality, we can borrow much closer to 2% a year, but for 30 years. So the whole cost of the loan scheme is much cheaper than the government claims. And even if it weren't, because we control the point at which graduates start to repay their loans, we could squeeze it down even further.
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A
This September, people are going to graduate from university and they will be the first cohort of undergraduates who have studied under this £9,000 tuition fee regime. Are they ever going to pay the loans back?
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E
Well, we know that a lot of them are going to pay the loans back, particularly the richer ones. So we think that about a third of them in total will pay back. Curiously, there's actually quite a big gender divide in that. So because men tend to earn more, roughly 60% of male graduates will repay their loans in full. But probably a third or a fifth of female graduates, the top earners, are going to repay their loans in full.
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A
Now, if Ed Miliband gets his way and introduces a cap of £6,000. Who's going to benefit from that?
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E
Again, it's the top earners. So roughly, the bottom third of men don't repay the loans at the moment. And they wouldn't repay even if we cut the tuition fee to £6,000 a year.
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So the poorest wouldn't benefit.
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The poorest third of men wouldn't benefit at all. Similarly, the poorest half of women would get no benefit at all. They don't repay now. They wouldn't repay if fees were cut to 6,000 pounds a year. The people who really benefit are the ones who already repay because they get the full £3,000 a year benefit of cutting the fee. So that means in practice, they would all finish paying off their loans a bit earlier. That's the top 60% of men and the top fifth or third of women.
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So the more you earn, the more you currently repay, the more you would benefit from this new cap of £6,000.
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Exactly.
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So is it fair to say that despite the massively increased fees, the new system is nearly as expensive for the taxpayer as the old one?
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E
So the tuition fee system is objectively a very expensive thing, because universities are a very expensive thing. It's billions of pounds a year. It certainly costs more than the coalition government said it would cost. But the idea that the current system costs more than the old system, for example, where the government provided a lot more of the cost, is almost impossible. It requires both an enormous spike in the cost of government borrowing and for a future government to decide to rapidly raise the income at which you start repaying your student loan. Those things have to happen together for it to be more expensive.
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So almost certainly the new system is saving the taxpayer money, which you would kind of hope, since it is asking students to pay more money.
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Exactly.
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The BBC's Chris Cook you're listening to More or Less, and I'm Tim Harford. Now, what could be more romantic than a relaxing cruise on the Mediterranean Sea? You take your loved one by the hands and recreate that magical Jack and Rose moment from Titanic. The salty sea breeze is whipping through your hair. The evening is enchanting. You learn to carve love hearts out of watermelons. Then the Michael Bubble tribute act, then the Michael Buble tribute act sings your song. It is perfect. Just you and that special person to whom you've pledged your heart. Or maybe that fit young pool attendant. Because according to research published in the Daily Telegraph, the typical cruise these days is less the Love Boat and more the Love Rat, a steamy orgy of depravity and betrayal. Where was I? Yes, the Telegraph's article makes it clear that. But nothing could be more catastrophic for the devoted monogamist than a cruise. One in five passengers admit to cheating on their partner on a cruise ship. To add insult to injury, in 80% of those cases, the partner was on board. Concerned listener Justin has emailed us to ask, should I cancel my cruise and save my marriage? Well, Justin, don't take any drastic action. Just lie back on your sun lounger and close your eyes while we look into these numbers. The survey was carried out by Cruise.co.uk, a website for cruise enthusiasts. It posted some questions about onboard sex on its forum and fewer than 300 people answered. First, the survey asked, have you ever had sex on a cruise? 81% of people responded yes. Which may not be surprising. It continued, was it with someone other than your husband or wife or partner? 17% of respondents said yes. And that's where the Telegraph gets its claim that one in five passengers cheats. But that's not what the question asked. For example, if you were single and had a fling on board, you'd have answered yes. And I'm sorry to drag the Daily telegraph into the 21st century, but a holiday romance isn't cheating on anybody if you were single when you started. For that matter, if the cruise was years ago and you were sleeping with the person who was your partner at the time but isn't your partner now, then you might also have responded yes. And that's not cheating either, unless you have a seriously Old Testament attitude to serial monogamy. And now, the real statistical bungle. The survey's next question. Was your husband or wife or partner on board at the time? 81% of people responded yes to that. And the Telegraph concludes from this that 80% of people have cheated while their partner was on board. But again, that's not what this number shows. Remember, 81% of people said they'd had sex, 83% said it was with their current partner or spouse, and then 81% said their partner or spouse was on board. So all the survey shows is that most people have had sex on a cruise with their partner. So, Justin, our dear listener, please don't cancel your cruise. It sounds like you might have a lot of fun. Now, let's get the Michael Bubble back on and stoke the engine. It's full steam ahead on the More or Less Love Boat. Since the best relationships involve constant little arguments, do please send your incessant nagging along to more or lessbc.co.uk no doubt one of the things you'll be pestering me about is the general election campaign that's due to be waged around the clock over the next few months. I have a cunning plan to pop up on Radio 4's news programs throughout the campaign, skewering the misleading statistical claims and counterclaims we already know will be being lobbed back and forth. But loyal listener Rosemary is ahead of the pack on this.
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I want to ask a very pertinent question.
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How many constituencies are genuinely safe? That is, the winning margin is so enormous and rock solid that all the
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votes for other parties combined wouldn't sweep the incumbent away. A lot of people don't bother to
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vote because they think their vote doesn't count.
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But if all the people who don't
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bother to vote actually voted, would any seat be safe? Rosemary, we have just the man to answer your question, the omniscient editor of BBC Political Research, David Cowling. He lives in the BBC's Millbank offices at the heart of Westminster. So I put your point to him. Are there any genuinely safe seats in the country anywhere where someone had received more votes than all of the other parties combined?
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Well, there are over 200 of those seats where in the 2010 general election, the winning candidate got 50% or more of the vote. Therefore, if all the other candidates, instead of being scattered amongst, you know, three or four parties, it all clustered and gathered around one other candidate, they still would not have been able to overturn it. So quite a substantial number of seats where they are won by 50% of
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the votes cast, that's about a third of all parliamentary seats. Now, Rosemary also says, well, there are people who could vote and don't vote, and what if those people turned out to the polls and they all voted, that would change the picture. So she also wanted to know how many seats there were where the candidate actually got more than 50% of the election electorate voted for the winning candidate.
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I cannot recall one. Certainly in Great Britain, whether somebody wins 50% of the electorate, it is very unusual. And especially, of course, it becomes more difficult to win with over half the electorate. In the time in the last 20 or 30 years when turnout itself has really come down dramatically from what it used to be. So I can't recall one, I'm afraid.
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This question of making voting compulsory, Rosemary's question, it sort of implies that if everybody turned out or if people were legally obliged to turn out, then everything could change. We could have very different parties voted in. Is there any reason to believe that things would be very different if turnout was 100%.
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I mean, it's a very important question. It's a rather difficult one to answer because there isn't an enormous amount of evidence around. However, when the 2001 election took place, you may remember, turnout collapsed to the lowest in over a century. The Today program decided to see what this was about. So they commissioned a poll, I think from icm, which was conducted exclusively amongst non voters. So it was after the election and they sought out people who hadn't voted and they said to them, look, we know you haven't voted, but if you had voted, how would you have voted? And it turned out that their voting was almost exactly mirroring what happened in the general election. So there didn't appear on that evidence to be anything to support the proposition that the only people, you know, all the people staying at home, were of one persuasion and if only they could be forced to come out and vote, then it would turn upside down the outcome of the election.
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Interesting. Although we should say that's just one poll and you never really know. And of course, and it was only the 2001 election, but, but still it's intriguing. Does the BBC have a definition of a safe seat?
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No.
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So that's because it's a movable feast. I would personally argue is about 20, a majority of 20% or more of the votes cast. Of the votes cast. So a 20% majority means that the winning person in the previous election, the election 2010, the winning person had a majority. The gap between her and the person who was second was 20% or more.
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Is this election historically abnormal or likely to be viewed in retrospect as historically abnormal?
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Well, it's causing me nervous exhaustion before the campaign's even started. I think this election is going to be a devil to predict. And why is that? Well, we have a first past the post system. As we know our system is not proportional. So that first past the post system can generate some interesting, some might say eccentric, results. And where we were in 2010 with three parties that were vying for our support, three main parties in Westminster, now we have four UKIP. Is there a big fat cuckoo that's crash landed into the Westminster nest, which is disrupting politics as usual? They may not win many seats, but they are currently out polling the Lib Dems who are actually in government. So that's a complication. We also have now the additional post referendum, big question mark about Scotland. The opinion polls currently suggesting that the SNP will eat hard into Labour's Share of the vote the Greens are beginning to rise. Nothing like the Ukip or the snp, but they're beginning to snap at the heels of Labour and the Lib Dems. When the vote is splitting 4, 5, 6 ways, it is a devil to
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predict David Cowling, the editor of BBC Political Research. A few weeks ago, after flippantly confessing my deep love for the Consumer Prices Index, I asked what your favourite statistics were and here are our favourites from your favourites. My favourite statistic is that half the people in this country are of below average intelligence. Incidentally, my second favourite statistic is that half the people in this country are of above average intelligence.
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B
My favourite statistic 85% of statistics 84.2%
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97% of all statistics are made up.
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Favourite statistic 100% of people who say X percent of statistics are made up think they are clever, funny and original.
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The average number of legs on a person is less than 2. I like it because it seems to be patently true, obviously incorrect and practically useless all at the same time.
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My favourite statistic is the average number of arms per person is less than 2.
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My favourite statistic is Bayes Law. I use it to manage my mental health all the time and every parent with teenage children needs to know it. The probability something terrible happens to teenagers when they go out? One in a million, I hope. The probability they forget to call or lose their phone 1 in 10. So if they've not called, the probability of something terrible having happened is one in a hundred thousand. I've used it so much that when we get cross with my daughter for forgetting to call, she simply says baes. However, it only goes so far. If they've not called the next morning, statistical rationality goes out of the window and panic takes over.
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Mine is the tfr, the total fertility rate of a population. This statistic, along with immigration and mortality data, allows us to make predictions about the demographic future of a population. It may also allow us to make predictions about the social and economic behavior of the population related to how long ago the TFR of the population fell from above 4 to a much lower number. This has now happened in almost all human populations. In the case of Britain it was in the late 19th century. In the case of Iran it was during the 1980s and China's decline began in the 1960s. It is well known, but seldom widely discussed, that once their TFR falls, populations enjoy what is known as a demographic dividend. GDP per capita has to begin to rise because there are fewer unproductive children relative to productive adults. Also, women are more likely to be employed in salaried work than in caring for children. And there is so much more I can go on and on about my enthusiasm for tfr.
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A
I am a psychiatrist in training. My favourite statistic to mention, although a terribly Sad1, is 15 to 20 years and it's the number of years your life expectancy is on average reduced if you have schizophrenia. It has become my favorite statistic to mention because it illustrates the reality of the disadvantage that faces the one in every hundred of us that lives with this most stigmatised and misunderstood of problems.
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F
As an artist, I'm working on a commission for the Eden Project, which is a mass community dance project. It will involve 500 dancers and the statistics suggest that we are only 10% human cells and 90% bacteria. That means that the average human has around 100 trillion microbes in and on their body. So with 500 dancers taking part, there will be 100 trillion times 500, which I think is 50,000 trillion doing the sums on a calculator and I do hope I've done my sums correctly. I came up with 5e16, which is very enigmatic. As such, I have used 5e16 microbes on the move as the title.
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A
Thank you to Mike, Nicola, kp, Chris, Hilary, Mike, Bill and Alastair. That is it for the current series of More or Less. We'll be back on Radio 4 on the 1st of May, but if you subscribe to our podcast, you'll be just fine because you'll still get the secret short episodes in the next few weeks. We'll be looking at whether humans will need to produce more food in the next 40 years than we did in the previous 10,000 put together. We'll also examine the true cost of Ebola, and I'm sure the global economy will get a look in from time to time, so please sign up via our website, BBC.co.uk more or less. And as I mentioned, we'll be watching the election campaign like hawks swooping down on our politician prey on Radio 4 news programmes when they least expect it. So do keep sending your statistical questions and answers and errors to more or lessbc.co.uk. our number Y eyesight is keen, but often not as keen as yours or that of loyal listener Linda Rastcliffe. There she was earlier this week, washing her cat's dish in the kitchen sink up in County Durham, with BBC2's Daily Politics show on in the background, her ears pricked up when in the middle of a discussion about school standards. With presenter Joe Coburn, she realised the Conservative MP Nadine Norris had got her maths in a muddle. Can you spot the mistake? 23% of secondaries requiring improvement. That's a very high number after five years in government.
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In a policy area that you say
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the Conservatives have done particularly well on.
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B
Well, I think it's an area which was a figure which, if you looked at that figure five years ago, was even worse. So I think what we're looking for, and I think all governments. That's one in four schools.
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D
Yeah.
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B
And I think before it was one in seven.
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A
Well done, Linda. Nadine Norris, See me after the program. Goodbye. And just a reminder that you can download more podcasts at BBC Co UK Radio 4.