DOS AND DON’TS OF DATA VIZA TALE OF PIES, DECEPTION AND MIND TRICKSIÑAKI PUIGDOLLERS SABINData Scientist

DON’T RESCALE PROPORTIONS!

x1.75 times bigger

Source: http://cadenaser.com/

15.1 + 70.7 + 15.2 = 101%

DO KEEP THE PROPORTIONS AS THEY ARE

YET ANOTHER EXAMPLE …

?

Source: Twitter, @ppmadrid

NOW IN A PROPORTIONAL SCALE

PSOEPARTIDOPOPULAR

Núm

ero

de P

arad

os

DON’T OMIT THE ORIGIN OF THE Y-AXIS

Where is the

Axis??

94 is not 0

Source: http://blog.rtve.es/http://mediamatters.org/

DO SHOW THE Y-AXIS FROM THE ORIGIN

Mill

ion

Dol

lars

50.66% 49.07%

THIS ALSO HAPPENS IN SCIENTIFIC PAPERS

This is a big difference, isn’t it?

According to the paper,

this should be 1.82

The value of Y (Rape Myth Acceptance)

varies between 1 and 5

There are values placed in the

wrong position

Source: Fox, Jesse; Bailenson, Jeremy N.; Tricase, Liz (2013). "The embodiment of sexualized virtual selves: The Proteus effect and experiences of self-objectification via

avatars". Computers in Human Behavior 29 (3): 930–938

THE REALITY IS SOMETHING DIFFERENTFace

It was not that different in the

end…

Remember:The value of Y

(Rape Myth Acceptance)

varies between 1 and 5

DON’T USE INVENTED OR TAILOR-MADE SCALES

How can this be a line?

Source: http://mediamatters.org/

DO PLOT DATA AS IT IS

DON’T USE DIFFERENT SCALES FOR THE SAME AXIS

Left Y-Axis (representing the non-smokers)

starts at 2

Right Y-Axis (representing the smokers)

starts at 3

Source: H. Wainer, Visual Revelations, Graphical Tales of Fate and Deceptions from Napoleon Bonaparte to Ross Perot

Disclaimer! This Graph is from a tobacco company

DO USE THE SAME SCALE TO MAKE DATA COMPARABLE

DON’T SHOW MEANINGLESS NUMBERSDON’T USE PIE CHARTS

193% ???That’s a big pie!

Source: http://mediamatters.org/

DON’T USE 3D

Perspective makes percentages look different

Source: http://imgarcade.com/1/misleading-circle-graphs/

SOME THINGS WE LEARNED AT SCHIBSTED

■ Know your audience and adapt the visualization to them

■ The title matters, it has to be attractive but not distracting

■ Select the most suitable plot, there is no one-plot-fit-all

■ Show only relevant information, crowded visualizations are misleading

■ Sometimes you can break the rules…

DO CHOOSE A VISUALIZATION FITTING YOUR AUDIENCE

Percentage of Sellers per segment

Slack channels sharing users

DON’T USE CROWDED PLOTS WITH MISLEADING INFORMATION

■ Too many elements

■ The colours are meaningless

■ The axes are misleading (not showing the origin)

DO SHOW ONLY WHAT IS IMPORTANT

■ Axes starting at 0

■ Only the necessary elements

GOAL Show the correlation of the

data points

… A DIFFERENT APPROACH

■ We don’t care about the value it’s OK to break the axis rule!!

■ The colours have a meaning

GOAL Show the distribution and density of the data points

WE ARE LOOKING FOR TALENT!

inaki.puigdollers@schibsted.com

Thanks, questions?

Data Scientist – Schibsted Product & Technology