Uncover mitigate bias data visualisation

Talk delivered at BrightonSEO/Measurefest in October 2024 titles "Uncover and mitigate bias in data visualisations".

This talk is suitable for marketers of all disciplines, providing a toolkits of tips, tricks and insights to uncover and mitigate bias in data visualisations.

The talk will become available on the BrightonSEO YouTube channel at a later date.

1. Uncover & mitigate
bias in data
visualisations.
Neil Barnes
PMG
https://www.slideshare.net/neil_barnes
https://www.linkedin.com/in/neil-barnes-54119327/

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2
Bias exists in three
core areas of data
visualisation. ANALYSIS
DATA
COGNITIVE
VISUAL

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3
We cannot eliminate
bias, but we can
uncover & mitigate.

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4
Datasets are often
incomplete, causing
survivorship bias.
DATA
COGNITIVE
VISUAL

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High Accuracy
High Precision
High Accuracy
Low Precision
Low Accuracy
High Precision
Low Accuracy
Low Precision
Accuracy
Precision
Accuracy &
precision enable
understanding of
survivorship bias.

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6
Critical thinking to
identify extent of
survivorship bias.

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Critical thinking
applied to Google
Analytics data.
Bias AccuracyPrecision
Cookie banner Low High
Ad blocker Low High
Browser cookie Low High
Data modelling Low High
Users vs people Low High
Attribution Low High
Bot traffic Low High
Sampling Low High

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The human brain
processes 35,000
decisions every day.
DATA
COGNITIVE
VISUAL

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Cognitive bias is the
human brain taking
shortcuts, to reach
decisions at speed.

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Framing effect

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Conversion rate has
doubled…

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… or 90% of our
audience do not
convert.

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Whilst conversion rate has doubled
YOY, 90% of our audience do not
convert. Continual improvement
provides an exciting growth opportunity.

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Causal illusion

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Correlation is
incorrectly implied as
causation.
P=0.64

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16
Increased ice cream
consumption
causing more shark
attacks?!

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Increased shark
attacks causing
people to eat more
ice cream?!

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P=0.61P=0.85
Air temperature is the causation

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Anchoring effect

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20
Our first reaction is
to panic that CPC
sessions are in sharp
decline.
This YearLast Year
CPC sessions479,310634,825

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21See the whole picture & mitigate anchoring
effect
This Year Last Year % change
CPC sessions 479,310 634,825 -24%
Spend £923,530 £1,006,122 -8%
Cost/session £1.93 £1.58 22%
Engagement % 53% 49% 8%
Revenue £4,406,517 £4,385,059 0%
ROAS 477% 436% 9%

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22
We can mitigate
visual bias, with a
high level of control.
DATA
COGNITIVE
VISUAL

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Scale manipulation

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Trend exaggeration
through a biased
scale.

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A fair scale provides
an unbiased view of
the visualisation.

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Bias can also occur
using an inconsistent
timeframe.

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Making trends
appear biased &
difficult to interpret.

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Correlation illusion

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There is no
correlation in this
dataset.
P=0.08

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A ‘best-fit’ trend line
introduces bias &
implies correlation.

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A ‘best-fit’ trend line
introduces bias &
implies correlation.

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A ‘best-fit’ trend line
introduces bias &
implies correlation.

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33
Visual distortion

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Pie & donut charts
introduce visual
distortion & bias.

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3 dimensional
visuals exaggerate
biases further.

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A bar chart provides
clarity & mitigates
bias.

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Colour choice can
bias how data is
visualised.

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Cognitive bias
introduced through
choice of colour.

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39
Cognitive bias
introduced through
colour shading.

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Accessibility is
critical, in mitigating
visual bias.

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41
Add symbol markers
to provide visual
distinction.

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Patterns provide
visual distinction to
bar charts.

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Alt text, to provide
text descriptions for
data visuals.

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44Tables & shapes aid accessibility
This Year Last Year % change
CPC sessions 479,310 634,825 -24%
Spend £923,530 £1,006,122 -8%
Cost/session £1.93 £1.58 22%
Engagement % 53% 49% 8%
Revenue £4,406,517 £4,385,059 0%
ROAS 477% 436% 9%

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45
Five takeaways to
uncover & mitigate
bias in visualisations.

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46
Bias exists in three
core areas of data
visualisation.
DATA
COGNITIVE
VISUAL

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47
High Accuracy
High Precision
High Accuracy
Low Precision
Low Accuracy
High Precision
Low Accuracy
Low Precision
Accuracy
Precision
Survivorship
bias in data can
be identified by
thinking critically.

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Cognitive biases:
Framing effect
Causal illusion
Anchoring effect

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49
Visual biases:
Scale manipulation
Correlation illusion
Visual distortion
Colour choice

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Accessibility:
Data markers
Patterns
Alt text
Tables & shapes

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51
Uncover & mitigate
bias in data
visualisations.

52. Thank you!
Neil Barnes
PMG
https://www.slideshare.net/neil_barnes
https://www.linkedin.com/in/neil-barnes-54119327/