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TIPS FOR BETTER
DATA VISUALISATION
Iman Eftekhari
Principal Consultant
iman.eftekhari@agilebi.com.au
www.agilebi.com.au
Agenda
• What is DV?
• Tips for more effective DV
• Q&A
What is Data Visualisation?
A Picture is Worth a Thousand Numbers
Thinking With Our Eyes
• 70% of body’s sense receptors reside in our eyes
• “The eye and the visual cortex of the brain fo...
How the Eye Works
• The eye is not a camera!
• Attention is selective (filtering)
• Cognitive processes
• Psychophysics: c...
Eyes vs. Cameras
• Cameras
• Good optics
• Single focus, white balance, exposure
• Full image capture
• Eyes
• Relative po...
Colour is relative
Same or different?
Colour is relative
Same!
Basics & Principles
Classification of Data Types
• N Nominal (labels)
• Fruits: Apples, Oranges, …
• O Ordinal
• Quality Rating: A, AA, AAA
• ...
Pyramid of Scales
Nominal
scale
Ordinal
scale
Interval
scale
Ratio
scale
Logical/
math
operations
×
÷
N N N Y
+
-
N N Y Y
...
Importance Ordering of Perceptual Properties
Effective Design
• Mapping data to visual attributes:
• Faster to interpret
• More distinctions
• Fewer errors
Mackinlay’s Expressiveness Criteria
• A set of facts is expressible in a visual language if:
The sentences (i.e. the visua...
Cannot express the facts
• Which colour is greater than the other?
Expressing facts not in the data
• Length is interpreted as a quantitative value
• Length of bar says something untrue abo...
Effective Design
• Importance Ordering
• Expressiveness
• Consistency
Relative Magnitude Estimation
Most accurate
Least accurate
Position (common) scale
Position (non-aligned) scale
Length
Slo...
Bertin’s Retinal Variables
Jacques Bertin, a French cartographer, Semiology of Graphics
Chart Chooser
http://labs.juiceanalytics.com/chartchooser/index.html
Colour Brewer
http://colorbrewer2.org
List of Recommended DV Tools
http://selection.datavisualization.ch
Q&A
Iman Eftekhari
iman.eftekhari@agilebi.com.au
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SYBIS - Data Visualisation

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Data Visualisation Tips

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SYBIS - Data Visualisation

  1. 1. TIPS FOR BETTER DATA VISUALISATION Iman Eftekhari Principal Consultant iman.eftekhari@agilebi.com.au www.agilebi.com.au
  2. 2. Agenda • What is DV? • Tips for more effective DV • Q&A
  3. 3. What is Data Visualisation?
  4. 4. A Picture is Worth a Thousand Numbers
  5. 5. Thinking With Our Eyes • 70% of body’s sense receptors reside in our eyes • “The eye and the visual cortex of the brain form a massively parallel processor that provides the highest-bandwidth channel into human cognitive centres” Colin Ware, Information Visualization, 2004 • Important to understand how visual perception works in order to effectively design visualisations
  6. 6. How the Eye Works • The eye is not a camera! • Attention is selective (filtering) • Cognitive processes • Psychophysics: concerned with establishing quantitative relations between physical stimulation and perceptual events
  7. 7. Eyes vs. Cameras • Cameras • Good optics • Single focus, white balance, exposure • Full image capture • Eyes • Relative poor optics • Constantly scanning • Constantly adjusting focus • Constantly adapting (white balance, exposure) • Mental reconstruction of image (sort of)
  8. 8. Colour is relative Same or different?
  9. 9. Colour is relative Same!
  10. 10. Basics & Principles
  11. 11. Classification of Data Types • N Nominal (labels) • Fruits: Apples, Oranges, … • O Ordinal • Quality Rating: A, AA, AAA • Q Quantitative • Interval (location of zero arbitrary) • Date, geometric point • Ratio (zero fixed) • Physical measurements, counts, amounts
  12. 12. Pyramid of Scales Nominal scale Ordinal scale Interval scale Ratio scale Logical/ math operations × ÷ N N N Y + - N N Y Y < > N Y Y Y = ≠ Y Y Y Y S. S. Stevens, On the Theory of Scales of Measurement (1946)
  13. 13. Importance Ordering of Perceptual Properties
  14. 14. Effective Design • Mapping data to visual attributes: • Faster to interpret • More distinctions • Fewer errors
  15. 15. Mackinlay’s Expressiveness Criteria • A set of facts is expressible in a visual language if: The sentences (i.e. the visualisation) in the language express all the facts in the set of data, and only the facts in the data. Mackinlay, APT (A Presentation Tool), 1986
  16. 16. Cannot express the facts • Which colour is greater than the other?
  17. 17. Expressing facts not in the data • Length is interpreted as a quantitative value • Length of bar says something untrue about data
  18. 18. Effective Design • Importance Ordering • Expressiveness • Consistency
  19. 19. Relative Magnitude Estimation Most accurate Least accurate Position (common) scale Position (non-aligned) scale Length Slope Angle Area Volume Color (hue/saturation/value) Spring 2010 I 247 19
  20. 20. Bertin’s Retinal Variables Jacques Bertin, a French cartographer, Semiology of Graphics
  21. 21. Chart Chooser http://labs.juiceanalytics.com/chartchooser/index.html
  22. 22. Colour Brewer http://colorbrewer2.org
  23. 23. List of Recommended DV Tools http://selection.datavisualization.ch
  24. 24. Q&A Iman Eftekhari iman.eftekhari@agilebi.com.au

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