'The benefits bill is spent on unemployed and disabled people'



It's true that the Department for Work and Pensions is the biggest-spending government department in the UK, spending £166.98bn in 2011-12. Of that huge sum, £159bn was spent on benefits – an increase of 1.1% on the previous year. That's 23% of all public spending.

But ask people where that money goes and the assumptions are that it's on unemployment or incapacity benefit. In fact, 41% of people think that the entire welfare budget goes to unemployed people, according to a recent TUC poll. In fact, half of UK benefit spending actually goes on state pensions. That is £74.22bn a year, more than the £48.2bn the UK spends on servicing its debt.

It's followed by housing benefit of £16.94bn and disability living allowance of £12.57bn. Jobseeker's allowance is actually one of the smaller benefits – £4.91bn in 2011-12. That is 3% of the whole benefits bill.

'You can fit the entire population of the world on the Isle of Wight'



It's become an accepted truth that you could fit the entire population of the world, shoulder-to-shoulder, on the Isle of Wight. But is it true?

The Isle of Wight is 380m square metres, so how many people could fit there? Well, you wouldn't get much room for personal space – and that's leaving aside the logistics and health implications of moving everyone on the planet to one place. But if we assume an average space of 0.5 square metres each – and that children take up half as much space as adults – then it could go like this:

There are 5.2 billion adults and 1.9 billion children in the world. The adults would take up 2.6bn square metres – and the children 475m square metres. And that doesn't take account of people who are obese, or starving. Together, that is just over 3bn square metres.

So, while you could get all the children of the world on to the Isle of Man (which is 570m square metres), for the entire population you need to go a little bigger. Like, say, South Georgia in the southern Atlantic Ocean. At 3.7bn square metres, we might even have a little room to spare.

Are we really being swamped with immigrants? Photograph: Alamy

'A third of the British population are immigrants'



Ask people in the UK how many immigrants there are and people tend to reply around a third – or, to be precise, a foreign-born population of 31.8%. This figure is from a huge international survey of migration perceptions, by Transatlantic Trends, which asked people in Britain, the US, Germany, Italy, Spain and France what they think about immigrants.

It also finds that people in the UK are more likely to believe "there are too many migrants" and that migrants are more of "a problem than an opportunity" than any of the other countries surveyed. And the figures don't change – more than half of the British population (57%) think there are "too many immigrants", a figure that has stayed nearly the same for the past four years. And that is higher in the UK than any other country.

In fact, that 31.8% figure is a wild over-estimate; in 2011, some 11.3% of the UK population were foreign-born.

'You're more likely to get bitten by a person than a dog'



Dog owners' forums and Facebook groups are fond of the aphorism that you're at more risk of being bitten by a human than a dog – but could that possibly be true? According to the NHS Information Centre, the exact numbers of human injuries are not recorded in the UK. The best estimates are anywhere between 4% and 23% of all injuries.

Meanwhile, the latest data shows that 6,447 people were admitted to hospital for dog bites in 2011-12 – a 5.2% rise on the previous 12 months. Of those, under-10s accounted for the highest rate of admissions by 10-year age group, with 17 per 100,000 population - 1,040 admissions. If you look at the historic data, that shows that in 1989-90, 991 were admitted – a 551% increase in total dog bite admissions in two decades.

To put it in perspective, there were 17.6m admissions to accident and emergency departments in 2011-12. For every million A&E treatments, there are 366 hospital admissions for dog bites. To add a bit more context, the RSPCA says there are 8.5m dogs in the UK; this means there are around 75 serious dog bite admissions to hospital for every 100,000 dogs.

They are not the only things people are bitten by, of course – arthropods (mosquitoes and midges, to you and I) are responsible for peaks in hospital admissions over the summer. But nevertheless, dog bites remain consistently high throughout the year. But if you focus on mammals entirely – which includes humans – dogs are clearly the majority of injuries, around 71%.

The treatment figures tell a story too. In short, children are more likely to get bitten on the face, requiring plastic surgery to reconstruct them, older people on the hands or lower body. Having said that, while both human and dog mouths host several hundred species of bacteria, most of the bacteria found in canines' mouths is not harmful to humans, making many dog bites less dangerous than human ones.

'NHS spending is protected'



It's a manifesto commitment of the Conservatives – that the coalition would never slash the budget of the NHS. Prime Minister David Cameron reiterated that in March in a speech where he promised: "We made a very clear promise before the last election that yes, we were going to have to take difficult decisions, yes, we were going to have to make some very difficult and painful cuts, but we wouldn't cut the NHS budget. I think it's really important for people to know that."

So, have they stuck to it? If you look at the raw numbers, there has been a slight increase. In 2010-11, NHS spending was £94.57bn, and £95.96bn the year after. But that doesn't take account of the rising cost of living – inflation – which was 2.38% over the two years.

It's partly tricky to work out because government spending is confusingly split into two halves: departmental expenditure limits (DEL) and annually managed expenditure (AME). You would have trouble getting someone in government to explain what that actually means but, in practice, DEL is the money that a department can predictably spend, such as its administration budget, while AME is less controllable, such as benefits or rising health costs. So, when ministers talk about cuts in spending, they often just mean the DEL portion of the pie. And just that bit is up by 0.02% after inflation – or steady.

But if you look at total spending (which is basically both bits added together), then spending on the NHS is down by 0.9% in real terms, with cuts of 1.17% in primary care and 1% in dental services. In fact, the chair of the UK statistics authority Andrew Dilnot, following a complaint by shadow health secretary Andy Burnham against health minister Jeremy Hunt, said he "concludes that expenditure on the NHS in real terms was lower in 2011-12 than it was in 2009-10".

'Benefit fraud costs us billions'



The British public reckon benefit cheats are a massive problem: a recent opinion poll showed Brits typically believed 27% of the welfare budget is lost to fraud. Given the public also think benefits are considerably higher than they really are, that all adds up.

The reality, though, is much less dramatic. The DWP publishes official estimates of fraud in the welfare system. The most recent publication estimated overall fraud at 0.7% of the benefits bill. At £1.2bn, that sum might – just – be said to count as "billions". But we should remember benefits can be underpaid as well as overpaid – and last year, those underpayments (arising from errors by either officials or claimants) added up to £1.3bn – more than the cost of fraud.

There are 3.1 million rats in the UK in urban areas. Photograph: Krishnendu Halder/Reuters

'You're never more than 6ft from a rat'



This old chestnut (or similar variants) has been with us for more than a century, and despite its fairly nasty implications, many of us believe it.

Thankfully, it's nonsense – even if you live in a city centre. The BBC's brilliant statistical team at More or Less examined the best estimates of rats in cities: outside and around houses (they're near 3% of homes), in sewers, and elsewhere. That gives an estimate of around 3.1 million rats in the UK in urban areas. Even if they were spread out absolutely evenly (though, of course, they're not), that would represent a good 5,000 square metres for each rat.

What would that mean for you? Happily, it would suggest you are typically around 164ft from a rat. Which is a bit better, right?

Safe as houses: is property the best investment? Photograph: Carl Court/AFP/Getty Images

'Houses are a great investment'



Why bother investing in a pension or the stock market when good ol' bricks and mortar give such a good return? House prices in the UK have rocketed over most adults' lifespans, prices fell only slightly in the crash, and demand is set to grow.

And yet. Looking even at the most straightforward figures, housing does not obviously outshine other investments. The real return (after inflation) on the FTSE 100 from 1984 (when it was introduced) to 2011 was about 105%. Housing over the same period returned around 101% on the same basis.

But there's more to it: houses require upkeep and upgrades – lots had extensions, improvements and redecoration to achieve those growing prices. That is not tackled in those simple figures, though neither is the fringe benefit of actually living in the house. Shares, meanwhile, often deliver a dividend along the way, increasing their overall return.

Housing isn't necessarily an awful investment – but it's no free lunch either.

'We don't make anything in the UK any more'



In the UK, we have a massive financial sector, a couple of coffee shops and a pile of fields – we just don't make anything any more. Or so goes the cry.

In reality, like most other developed economies (even Germany), our service sector is the largest component of our economy. But making things is still more common than you might think.

According to figures from the government and the Bank of England, the UK's manufacturing sector is bigger than its financial services sector. Manufacturing contributes around 11% of GDP, versus around 9% from the City. Contrary to what you might think, the biggest sector isn't heavy engineering (though there is plenty of that), but food and drink manufacture.

Despite the country's reputation as a "green and pleasant land", though, the UK doesn't grow that much: agriculture contributes less than 1% to GDP.

'Rich people move abroad to dodge taxes'



A constant mantra when discussing taxing the rich is whether they will simply stop working, or move overseas, if they are taxed too highly. This was used to justify cutting the 50p tax rate, among other policy decisions.

The arguments on tax and economic growth are tricky, and every side can pick out something to show. But on the specific question of whether rich people move to pay less tax, the evidence is pretty good.

People are pretty resistant to moving: there are language and cultural barriers, people have friends and families, their children in schools, and more. The US Center of Budget and Policy Priorities examined whether wealthy people moved between different US states – an easier move than switching country – if taxes went up.

They found almost no movement, even for the biggest tax hike, which raised $3.8bn (£2.5bn); only around 70 extra high earners moved, knocking around $16.4m (£10.7m) off the total.

The thing that might tempt the rich to move? According to the researchers, the biggest draw was cheaper housing elsewhere.

Facts Are Sacred by Simon Rogers is a visual guide to the data that shapes our lives. A print edition is available at guardian.co.uk/bookshop for £13 (rrp £20) and an iPad exclusive interactive edition is available from the iBookstore for £9.99.

• This article was amended on 25 April 2013 because several of the numbers used in the calculations in the section under the subheading "You can fit the entire population of the world on the Isle of Wight" were incorrect in the original version; the corrected figures are 1,000 times greater than the figures originally given.