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Pie charts

52 replies

DadDadDad · 09/11/2015 22:29

Not a language peeve for once, but still a point for pedantry. What is wrong with this picture? (Not the made-up data - that's me trying to be funny - but what's wrong with the way it's presented).

Pie charts
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DadDadDad · 09/11/2015 23:38

I assume you are talking about the DM one! (Mine in the OP was meant to be rubbish).

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DadDadDad · 09/11/2015 23:42

Milk - that rather confirms my point - the closer you get the perspective to flat, the easier it is to see the angles accurately. So, why not make it flat?

I honestly think 3D charts appeal to those who content is weak who want to compensate with something that looks fancy. As someone implied earlier, a real mathematician would keep it 2D.

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outputgap · 09/11/2015 23:46

That DM one is a disgrace. Pie charts show proportions of a whole, hence the bloody whole pie. Gah.

And I'm totes with you on the 2D. But I used to produce and check economic stats and charts. Happy days.

SwedishEdith · 09/11/2015 23:58

That DM one is a disgrace. How come only Costa gives a decent amount of caffeine in coffee?

DadDadDad · 10/11/2015 00:08

Yes, the beauty of the coffee chart is that if I worked at Nero and decided to up the caffeine in my coffee as a selling point, the slices of the pie for the other three would all shrink even though they had left their caffeine amounts unchanged! So I could make it look like they were all cutting down their caffeine.

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StealthPolarBear · 10/11/2015 06:14

Well to some extent that's how a real pie chart works (although the caffeine thing is ludicrous). If one component increases then it increases the whole.
If I spend £100 one day, £50 on books and £50 on make up, books gets 50% and half the pie. If the next day I spend £50 on books and £150 on make up, books gets .25 of the pie even though I actually spent the same amount. The portions of coffee in the coffee chart can't relate to the amount of caffeine as nothing is a proportion of a whole.
I tried to think of a stupid example but this is a real issue I deal with at work.

mammmamia · 11/11/2015 01:00

Yes Dad. I meant the DM one.
Yet another reason never to read the DM.

DadDadDad · 11/11/2015 07:26

Ha! Yes, next time we get someone on Chat asking why everyone is so anti the DM, you can chip in "and on top of all that, they abuse pie charts!" Grin

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WMittens · 11/11/2015 21:33

I'm sorry to disagree but I really did get those proportions from your original pie chart.

Same here.

Generally, humans can adjust for depth perception. I agree that a 3D element (if too extreme) is distracting and gimmicky, but it doesn't radically distort the information.

it's still meaningful as you can whip out a protractor and find for yourself the percentage for each category.

If anyone is having to do that then the information has been badly presented. If a pie chart is sufficient to display the information, then approximate proportions gleaned at a glance should usually be enough anyway. If the numbers are that essential, don't delete the values!

I find, at least for the recipients of the MI I produce, the charts are just for the barest feel of what's going on, and if they want more they ask for the raw data. In the words of Chandler's boss in Friends: "to summarise, the lines go up so I'm happy!" That doesn't really relate to pies though.

WMittens · 11/11/2015 21:35

The portions of coffee in the coffee chart can't relate to the amount of caffeine as nothing is a proportion of a whole.

It's slightly daft, but it still conveys usable information.

PurpleDaisies · 11/11/2015 21:39

How disappointing wmittens. I was really hoping I was some sort of savant with my spectacular ability to read a 3d pie chart. Grin

StealthPolarBear · 11/11/2015 22:12

I disagree by presenting it like that they imply proportions of a whole and you then have to work out that it's nothing of the sort.

DadDadDad · 11/11/2015 22:18

I disagree with the statement that going 3d doesn't radically distort the information.

Anyway, I feel one more experiment coming on to test mittens and purple. Back to my spreadsheet, to concoct some fiendish pies... Brew

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PurpleDaisies · 11/11/2015 22:20

dad I posted that I thought that parking represented 25% of the total before you revealed the answer. I don't know why you think I'd be making that up.

StealthPolarBear · 11/11/2015 22:25

Maybe indiciduals have super powers but charts should convey information clearly, to everyone. 3d pie charts do not. There is a guy who is the guru on this wish I could remember his name

DadDadDad · 11/11/2015 22:27

I was sceptical, but I certainly didn't accuse you of making it up, as I did see that you said it was very close to 25%.

My idea of an experiment was partly to see if that was a one-off, partly to address mitten's points. But you're perfectly free to walk away now with your geometric reputation intact. Wink

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elephantoverthehill · 11/11/2015 22:30

If you want to make a 'portion of the pie' look bigger, colour it red, if you want to make another look smaller, colour it blue. Red cars look bigger than blue cars. If you then put the red to the foreground in your 3-d pie chart, voila!

DadDadDad · 11/11/2015 22:32

stealth - as soon as I read your comment I has an inkling who you are talking about, but I couldn't remember his name either. Grin A bit of googling jogged the memory, and I bet you were thinking of Edward Tufte

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StealthPolarBear · 11/11/2015 22:40

Yep tufty that's him :o

DadDadDad · 11/11/2015 22:42

Never read anything he's written Sad

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emwithme · 11/11/2015 22:53
Pie charts
DadDadDad · 11/11/2015 22:55

Oh dear, just realised my previous post could be read as an instruction "You should never read...", when it was me being lazy and really meaning "I've never read..."

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senua · 11/11/2015 23:10

Are we supposed to be guessing the areas on the tarte au citron? I would say, given the markings on the tin foil Grin*, that
pie I have eaten = 30%.

*Or is this a trap? I don't trust D^3. Is he being sneaky?

DadDadDad · 11/11/2015 23:18

That tarte has nothing to do with me. Anyway, you are sure it's not a custard tart?

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senua · 11/11/2015 23:22

Ooops, hadn't spotted that it wasn't you! Blush It's definitely not a custard pie.

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