Data Visualization Jeffrey Heer Stanford University Set A Set B - - PowerPoint PPT Presentation

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Data Visualization Jeffrey Heer Stanford University Set A Set B - - PowerPoint PPT Presentation

Aug 14, 2022 43 likes •465 views

a brief introduction to Data Visualization Jeffrey Heer Stanford University Set A Set B Set C Set D X Y X Y X Y X Y 10 8.04 10 9.14 10 7.46 8 6.58 8 6.95 8 8.14 8 6.77 8 5.76 13 7.58 13 8.74 13 12.74 8 7.71 9

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SLIDE 1

a brief introduction to

Data Visualization

Jeffrey Heer Stanford University

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SLIDE 2

Set A Set B Set C Set D

X Y X Y X Y X Y 10 8.04 10 9.14 10 7.46 8 6.58 8 6.95 8 8.14 8 6.77 8 5.76 13 7.58 13 8.74 13 12.74 8 7.71 9 8.81 9 8.77 9 7.11 8 8.84 11 8.33 11 9.26 11 7.81 8 8.47 14 9.96 14 8.1 14 8.84 8 7.04 6 7.24 6 6.13 6 6.08 8 5.25 4 4.26 4 3.1 4 5.39 19 12.5 12 10.84 12 9.11 12 8.15 8 5.56 7 4.82 7 7.26 7 6.42 8 7.91 5 5.68 5 4.74 5 5.73 8 6.89

[Anscombe 73] Summary Statistics Linear Regression uX = 9.0 σX = 3.317 Y2 = 3 + 0.5 X uY = 7.5 σY = 2.03 R2 = 0.67

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2 4 6 8 10 12 14 5 10 15 2 4 6 8 10 12 14 5 10 15 2 4 6 8 10 12 14 5 10 15 2 4 6 8 10 12 14 5 10 15 20

Set A Set C Set D Set B

X X Y Y

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SLIDE 4

1826(?) Illiteracy in France, Pierre Charles Dupin

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SLIDE 5

cabspotting.org

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SLIDE 6

Wikipedia History Flow (IBM)

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SLIDE 7

Wikipedia History Flow (IBM)

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The Value of Visualization

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SLIDE 9

Three functions of visualizations

Record: store information

  • Photographs, blueprints, …
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Galileo’s drawings of the phases of the moon from 1616 http://galileo.rice.edu/sci/observations/moon.html

Drawing: Phases of the moon

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Answer question

Gallop, Bay Horse “Daisy” [Muybridge 1884-86]

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SLIDE 12

Three functions of visualizations

Record: store information

  • Photographs, blueprints, …

Analyze: support reasoning about information

  • Process and calculate
  • Reason about data
  • Develop models and hypotheses
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SLIDE 13

In 1854 John Snow plotted the position of each cholera case on a map. [from Tufte 83]

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Cholera outbreak

Used map to hypothesize that pump on Broad St. was the cause. [from Tufte 83]

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Three functions of visualizations

Record: store information

  • Photographs, blueprints, …

Analyze: support reasoning about information

  • Process and calculate
  • Reason about data
  • Feedback and interaction

Communicate: convey information to others

  • Share and persuade
  • Collaborate and revise
  • Emphasize important aspects of data
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SLIDE 16

1856 “Coxcomb” of Crimean War Deaths, Florence Nightingale

“to affect thro’ the Eyes what we fail to convey to the public through their word-proof ears”

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The Language of Visualization

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Detecting Brightness

Which is brighter?

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Detecting Brightness

Which is brighter?

(128, 128, 128) (144, 144, 144)

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Detecting Brightness

Which is brighter?

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Detecting Brightness

Which is brighter?

(134, 134, 134) (128, 128, 128)

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SLIDE 24

Just Noticeable Difference

Many continuous variations are perceived in discrete steps

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SLIDE 25

Steps in font size

Sizes standardized in 16th century

a

a

a

a

a

a a a a a a a a a a a

6 7 8 9 10 11 12 14 16 18 21 24 36 48 60 72

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SLIDE 26

Information in color and value

Value is perceived as ordered

Encode ordered values Encode continuous variables [but not as well]

Hue is normally perceived as unordered

Encode categories using color

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Which best encodes quantities?

Position Length Area Volume Value (Brightness) Color Hue Orientation (Angle) Shape

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Compare area of circles

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Compare length of bars

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Most accurate Position Length Slope Angle Area Volume Least accurate Color hue-saturation-density

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Deconstructing Visualizations

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Playfair 1786

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Time-Series Chart

x-axis position: year y-axis position: currency color: imports/exports ratio

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Wattenberg 1998

http://www.smartmoney.com/marketmap/

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SLIDE 35

Treemap of the Stock Market

rectangle area: market capitalization rectangle position: market sector, market cap color hue: loss vs. gain color value: magnitude of loss or gain

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Minard 1869: Napoleon’s march

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SLIDE 37

+

Single axis composition

=

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SLIDE 38

y-axis: temperature x-axis: longitude / time

Mark composition

+ =

temperature over space/time

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SLIDE 39

y-axis: longitude x-axis: latitude width: army size

+

Mark composition

+ =

army position (lat/lon) and army size (width)

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SLIDE 40

longitude latitude army size temperature latitude / time

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SLIDE 41

Minard 1869: Napoleon’s march

Depicts at least 5 quantitative variables. Any others?

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Summary

Effective visualizations can help us record, analyze, and communicate data Creating visualizations requires modeling data and applying appropriate visual encodings and interaction techniques. As you encounter visualizations in the world, try to deconstruct what you see. What are the underlying data and visual encodings?