Uncover mitigate bias data visualisation

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

Copyright 2024 PMG Worldwide LLC. All rights Reserved
2
Bias exists in three
core areas of data
visualisation. ANALYSIS
DATA
COGNITIVE
VISUAL

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

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

5
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.

6
Critical thinking to
identify extent of
survivorship bias.

7
Critical thinking
applied to Google
Analytics data.
Bias Accuracy Precision
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

8
The human brain
processes 35,000
decisions every day.
DATA
COGNITIVE
VISUAL

9
Cognitive bias is the
human brain taking
shortcuts, to reach
decisions at speed.

10
Framing effect

11
Conversion rate has
doubled…

12
… or 90% of our
audience do not
convert.

13
Whilst conversion rate has doubled
YOY, 90% of our audience do not
convert. Continual improvement
provides an exciting growth opportunity.

14
Causal illusion

15
Correlation is
incorrectly implied as
causation.
P=0.64

16
Increased ice cream
consumption
causing more shark
attacks?!

17
Increased shark
attacks causing
people to eat more
ice cream?!

18
P=0.61
P=0.85
Air temperature is the causation

19
Anchoring effect

20
Our ﬁrst reaction is
to panic that CPC
sessions are in sharp
decline.
This Year Last Year
CPC sessions 479,310 634,825

21
See 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%

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

23
Scale manipulation

24
Trend exaggeration
through a biased
scale.

25
A fair scale provides
an unbiased view of
the visualisation.

26
Bias can also occur
using an inconsistent
timeframe.

27
Making trends
appear biased &
difﬁcult to interpret.

28
Correlation illusion

29
There is no
correlation in this
dataset.
P=0.08

30
A ‘best-ﬁt’ trend line
introduces bias &
implies correlation.

31
introduces bias &

32
introduces bias &

33
Visual distortion

34
Pie & donut charts
introduce visual
distortion & bias.

35
3 dimensional
visuals exaggerate
biases further.

36
A bar chart provides
clarity & mitigates
bias.

37
Colour choice can
bias how data is
visualised.

38
Cognitive bias
introduced through
choice of colour.

39
Cognitive bias
introduced through
colour shading.

40
Accessibility is
critical, in mitigating
visual bias.

41
Add symbol markers
to provide visual
distinction.

42
Patterns provide
visual distinction to
bar charts.

43
Alt text, to provide
text descriptions for
data visuals.

44
Tables & 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%

45
Five takeaways to
uncover & mitigate
bias in visualisations.

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

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.

48
Cognitive biases:
Framing effect
Causal illusion
Anchoring effect

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

50
Accessibility:
Data markers
Patterns
Alt text
Tables & shapes

51
Uncover & mitigate
bias in data
visualisations.

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

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