Common mistakes in data visualizationAmedee Van
GasseBarCampGhent319 December, 2009
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The power of data visualization
Chinese proverb: One Picture is Worth Ten Thousand Words
The Fast-Food Information Age
Pr0n for the stats junkPointy-Haired Boss
Twitter: Infograph of the day (@bnox)
What Makes Good Information Design?
Interestingness
Function
Form
Integrity
Interestingness: relevant, meaningfull, newFunction: easiness,
usefulness, useability, fitForm: beatty, structure,
appearanceIntegrity: truth, consistency, honesty, accuracy
Interesting + function = experimentFunction + form = sketchForm
+ integrity = eye-candyIntegrity + interesting = proof of
concept
Not interesting = boringNot functional = uselessNo form = uglyNo
integrity = rubbish
With Great Power...
... Comes Great ResponsibilityLook for the Hidden Agenda
Trust No One
Lies, Damned Lies, and Statistics
Let's just face it:
Why do we lie?
Charts, infographics,... are only a simplified representation of
a complex reality
Compare with maps: they are also (white) lies
Used to convice others
Because it looks cool
Because we don't know any better
The axis are (not) your allies
Y axis starts at 500. Why 500?
Gradients
Grey on grey
Original chart has animation...
Why?
December = 1/5 size of January
= CRISIS!!!
Fear, Uncertainty and Doubt
Convince employees of needed budget cuts
Or... just blind faith in Excel???
What really happened
2008 up to Q3 was an exceptionally good year
Yes, there was a crisis, but...
We went to 1/2, not to 1/5
Excel bug: lowest value on Y-axis is magic...
What we saw in the meeting
versus 2008: - 1,3 %versus OB : + 0,6 %
47.988
47.115
47.385
2008
OB
2009
No scale
Why start at 40.000? Why not 30.000 or 45.000?
3D adds no value
A more accurate version
Scale added
Starts at 0
No 3D
versus 2008: - 1,3 %versus OB : + 0,6 %
You need X-Ray Vision for this one
Confession: I made this one
What if executed > planned? -> invisible!
Better chart: bars (executed) + lines (planned)
Pie chart hell
I made these too!
3D
Gradients
Could have been combined with previous chart
Combining the two previous charts
The donut: evil twin of the pie
Psychedelic
Hard to compare series
Can't get enough pie?
Only one thing is worse than one pie: two pies
Little information
You can tell your story with one chart
Pies are to scale
Pretty colors
3D: same diameter?Perspective?
The Mother of all Pie Charts
http://www.slideshare.net/netlash/old-media-vs-new-media
Sorry, @netlash, but this one really sucks
Why are Greece and Germany the same size?
Red = good or bad?
Lots of comments on InformationIsBeautiful.net
The original chart
Boring
Ugly
Easy to understand
By the way, did I already tell you that I really hate pie
charts?
The only good pie charts
Pac Man Pie: @flexyflow
Want to see some more silly charts?
Spiderman loves this one!
Radar chart
Hard to read
Needs a lot of tweaking
Ugly even with perfect data
3D: Manhattan chart
You can always go... downtown
3D: unstacked area chart
This one comes with X-Ray glasses
Can you see S3 (yellow)?
Use a 2D line chart!
Some practical tips
Colors
Axes, legend & title
Logarithmic scale
Colors
No gradients in background
Background contrasts with objects
Use color only when needed
Different color = difference of meaning in data
Soft colors + bright/dark for highlights
Colors
Stick with a single hue
Non-data just visible enough
Avoid red+green (colorblind)
Leave special effects to Hollywood!!!
And the Oscar goes to...
Axes, legend & title
X Axis: Category or Value?
Line charts or XY Scatter charts?
Zero-based or not?
Second Y axis?
Good title and axis labels = no legend needed
If your chart needs a legend, it is a bad chart
Axes gone wrong
X axis is time + location
X and Y axes ar not linear
A (bad) joke from http://graphjam.com
Logarithmic scale
Nonlinear stimulus-response: 10x pay raise makes you only 2x
happier
Avoid unless you know what you are doing
Can't be used with 0 in data
Use a trick: add 0.001
General tips
What is your message?
Who is your audience?
Prepare your data
Don't have blind faith in your software
Links
http://peltiertech.com/WordPress/category/chart-bustershttp://chandoo.org/wp/category/visualization/http://graphjam.com/http://www.informationisbeautiful.net/http://www.smashingmagazine.com/2009/09/11/
25-useful-data-visualization-and-infographics-resources/http://www.smashingmagazine.com/2007/08/02/
Data-visualization-modern-approaches/
Muokkaa otsikon tekstimuotoa napsauttamalla
Muokkaa jsennyksen tekstimuotoa napsauttamallaToinen
jsennystasoKolmas jsennystasoNeljs jsennystasoViides
jsennystasoKuudes jsennystasoSeitsems jsennystasoKahdeksas
jsennystasoYhdekss jsennystaso
TON x1000
08/20071093
09/20071037
10/2007970
11/2007909
12/2007953
01/20081078
02/20081159
03/20081287
04/20081276
05/20081207
06/20081316
07/20081269
08/20081166
09/20081200
10/20081028
11/2008758
12/2008645
01/2009678
02/2009673
03/2009659
04/2009587
05/2009575
06/2009606
07/2009748
08/2009868
09/2009919
10/2009926
11/2009933
12/2009897
Planning migratie Notes -> Exchangeweekaantal mailboxen
gemigreerdal gemigreerduitgevoerdniet gemigreerdcumul gepland
35/20072273316173
36/2007951353030210
37/20072281172904327
38/20073441072762440
39/20074511562639622
40/20076081822453820
41/200779313723251062
42/200792929820341360
43/2007122822318501574
44/2007145611917421698
45/2007157021715351928
46/2007179312013872062
47/2007191423011592304
48/200721562628892558
49/200724192416562799
50/200726602436703050
51/200729022484843279
52/2007315004843279
1/2008315004843279
2/2008315005063279
3/20083112514933327
4/20083163314323358
5/2008319404323358
6/20083190524193376
7/2008324204193376
8/2008323004263376
9/20083232234013399
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11/2008325604033399
12/20083256483053447
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14/20083362661813513
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16/2008301416883558
17/2008303068203624
18/200830980203624
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20/200830981193624
21/20083106903644
2008OB2009
YTD 10/2009 (in K)479884711547385
