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Zeroes and ones, part five

13 Apr

This week on Journalists’ Adventures in Maths: percentage changes are not reversible, or why a 75% rise from 4 to 7 is not a 75% fall from 7 to 4.

Dutifully checking the numbers* in the copy as they come up, I first get a result at variance with the reporter’s:

and then, by swapping the numbers around, get one that agrees:

However, the minus sign at the start of the second answer is the clue: the numbers in that sum are declining from over 400,000 to less than 300,000. But the copy talks about a rise.

The same thing happens with the second pair of numbers: the percentage rise is calculated as though it were a percentage fall.

Why is it not the same? The difference between 8,276 and 12,092 is always constant: 3,816. But in a percentage, of course, you can relate that constant difference to different comparators, and 3,816 is a much larger proportion of 8,276 than it is of 12,092.

This will hardly come as news to people who can do maths. But for arts-heavy newsrooms, this is slightly more perilous territory than the answer just being wrong – it is wrong, but it seems right if you do the sum the wrong way round. You need the strength of mind to remember which number you’re starting with and stick with it. It seems somewhat analogous to the evergreen error of mistaking ancestors for descendants, or confusing “overestimating” and “underestimating”. It’s not just the relationship between the two things that’s important, but the direction of travel too.

*Use of a percentage calculator is highly recommended, of course; I like this one, with its clear, question-based approach.

Zeroes and ones, part four

27 Nov

Q: Looking at the selected paragraphs below, and before doing any Googling, is there anything wrong with this article that can be determined simply from the evidence in front of you? Answers below

A: Not a particularly difficult one by the standards of what HeadsUp calls “implied mathematics“. If Hella Pick is 90 next spring, she’s 89 now. That means she was born in 1929. If she was born in 1929, she can’t have been 37 in 1980: she would have been in her 50s. So either her age or the date of Tito’s death is wrong. A quick bit of Googling would then tell you Tito indeed died in May 1980; so Ms Pick’s age at the time can be quietly removed from the copy. “… then 51 and working for the Guardian” somehow sounds much less glamorous.

Zeroes and ones, part three

11 May

One of the occupational hazards of being a journalist is that when a howler appears in the paper, all your friends know exactly who to call. Especially when they’re highly qualified science and maths graduates, and especially when the howler in question is a pretty glaring failure to check the sums.

So when this the first paragraph appeared in an article from the US office:

Screen Shot 2016-04-27 at 10.04.07

Followed by this information in the third paragraph:

Screen Shot 2016-04-27 at 10.04.25

Followed by this handy graphic as an explainer:

Screen Shot 2016-04-27 at 10.04.16

It wasn’t long before this appeared on my Facebook page:

Screen Shot 2016-05-09 at 12.51.30

Fortunately, because they’re all highly qualified science and maths types, when the bumbling former English student has questions, they have the explanations ready to hand:

Screen Shot 2016-05-09 at 12.51.43

So, for future reference: any percentage increase from 0% to any higher percentage is an infinite increase; but any percentage-point increase from 0% to a higher percentage is as simple a sum as can be: <higher percentage> – 0.

Meanwhile, the web news production editor has just sent this chastening email round to all subs:

A common error has popped up again so I just wanted to remind everyone that converting differences in temperatures is different to converting actual temperatures.
For example:
A temperature of 2C is 35.6F
but …
a difference in temperature of 2C is 3.6F.
 Thank goodness my friends didn’t see that story before it was corrected.


Zeroes and ones, part two

31 Oct

I love it when our media commentator goes off on a theme. Editing writers who have let themselves off the leash is always enjoyable, and his stream-of-consciousness style is at its best when he’s got hold of a metaphor and is running with it.

This piece – only a 240-word sidebar to his main column – is about the BBC payoffs row: the large amount of licence-payers’ money given as golden goodbyes to departing executives and the furious backlash that has resulted from them. That money could have been spent on all sorts of worthwhile things, the media has chorused, using the usual benchmarks: Downton Abbey episodes, schoolbooks, hospital beds etc. Last week, though, the BBC came out fighting, and countered the criticism with a comparison of its own. As the media commentator puts it:

Picture 17

And that’s all the media commentator needs to mint a new currency of comparison, the unit of exchange being the cost of televising Sunderland v Newcastle at the Stadium of Light: one match equals one “Light”.

Picture 18

When writers have got the bit between their teeth, the standard advice for editors is to keep out of their way and let them flow. And that’s good advice on the whole: intervening to correct fragmented sentences or very long paragraphs can kill the whole experience, and bring “correctness” and “readability” at the expense of enjoyment. But mistakes – actual mistakes – are a different matter. Maybe it’s my dorkish sub-editor’s soul, but I can’t fully enjoy a comic or passionate rant when a dangling modifier points all the ire in the wrong direction or there’s a glaring malapropism in the punchline. A greengrocer’s apostrophe can spoil a joke almost as much as it spoils an editorial. So the skill, actually, is to intervene just enough – to unobtrusively correct a fact or a timeline, say. Or, in this case, to correct the arithmetic.

Let’s look at what a “Light” is worth again. If £3.8m is “about half of what of what other TV networks would pay for televising the first half of  a Premiership football match”, that’s £3.8m per quarter, in effect, or £7.6m per half. The total cost of a match would be £7.6m x 2; therefore one Light equals £15.2m.

But that doesn’t seem to be how it works in the article. If BBC News costs £61.5m, that’s nowhere near as much as 10 Lights: more like four. Same with BBC4: £70.2m is less than 5 Lights, not more than 10.

And hang on a minute: did Lord Patten really say “half of what of what other TV networks would pay for televising the first half of  a Premiership football match”? That’s a funny way to put it – a lot of halves. That’s actually strange enough to need some investigation.

And lo and behold, the original article proves that doesn’t appear to be what he said. Per the furniture:

Picture 19

Mystery solved. But wait – what’s this in the body text?

Picture 20

So, he did say half of a half? What’s going on here? I thought I was just on for a quick tidy-up of a 240-word sidebar. But now, out of nowhere, we’re into a full-blown re-investigation of a completely different article from another desk whose content is at variance with its furniture (and which is also short an apostrophe in the standfirst). Can’t just leave it like that. Sigh.

Right: further scrutiny of this new article has revealed an actual hard number we can work from:

Screen shot 2013-10-29 at 18.12.48

Aha. So, allowing for typical politicians’ numerical exaggeration (and journalists are not in much of a position to criticise anyone else about that), £3.8m is indeed, roughly, the cost of televising half a Premier League match. Good: just need to email the media desk with suggested corrections for this piece, go back to my piece and write around the quote to fix it.

Except that – dammit – we’re still not quite there. If £3.8m is right (ish), the sums still aren’t. Look at the maths once again. The cost of BBC News, £61.5m, isn’t exactly “less than 10 Lights” if you take “less than 10” to mean nine-point-something and one Light to be £7.6m: it’s barely over eight. But it is pretty close if you go with the real £6.6m figure – which is mentioned nowhere in this piece. Moreover, BBC4’s budget of £70.2m isn’t “10 Lights and a bit of injury time” if one Light is £7.6m; and if one Light is £6.6m, it’s closer to 11 Lights than 10 – not just a bit of injury time but almost a whole extra hour.

Never judge an article by its word count. Man, why did I pick this one up?

Zeroes and ones

2 Jun

And the fact box read:

Picture 9

That’s faithfully transcribed from the data, supplied from an authoritative-looking source. And this is inward investment into China, so we are talking about serious money. But look at the subheading, as provided in the original: “$bn”. Then look at the commas in the figures: commas, not points. That means that Japan’s investment position in China in 2010 was $106,303,000,000,000. One hundred and six trillion dollars.

That’s a sizeable chunk of inward investment. No wonder the Shanghai skyline is shooting up so fast. It’s also about seven times larger than the national debt of the United States, and approximately 30% larger than the GDP of the entire world. And that’s before you get to the US’s own contribution to the Chinese economy, apparently a healthy  63 trillion dollars. You begin to suspect that something might be wrong.

Of course – all together now – you know what they mean. They mean 106 billion dollars; the table needs to say $m, not $bn. But that’s not what they said. There’s no descriptivism in maths. Billion is not “widely understood to mean million in informal or conversational usage”. It means billion.

Numbers, notoriously, provoke a certain amount of fear in the journalistic profession, stuffed as it is with arts graduates who quail inwardly at the sight of a percentage sign. But in many ways, it’s actually comforting to find oneself working in a system of communication where clarity is still prized over ambiguity.