Common visualization Issues & how to fix them

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Pamela Cameron
6 years ago
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1 CSE6242 / CX4242: Data & Visual Analytics Common visualization Issues & how to fix them Duen Horng (Polo) Chau Assistant Professor Associate Director, MS Analytics Georgia Tech Partly based on materials by Professors Guy Lebanon, Jeffrey Heer, John Stasko, Christos Faloutsos

2 Student of Edward Tufte 2

3 Also Highly Recommended:

4 Bar Charts 4

5 Bar Charts The color scheme reminds you of what? 4

6 Better than Christmas (Use color brewer to find good color schemes) 5

7 Company Profits 6

8 Company Profits Don t show profits in red!! Think carefully about your color choices. 6

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11 Misleading Bar Charts 8

12 Vertical axis of bar charts should start at 0, almost always 9

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14 Disorienting color bars 10

15 Use gradation 11

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17 Avoid Tilted or Rotated Labels 12

18 Bars Can be Horizontal 13

19 Bars Can be Horizontal When labels are hard to read, try horizontal layout. Don t settle for the default. 13

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21 Line Charts (a.k.a. fever lines) Can you improve the tick labels? 15

22 Use ticks at common intervals (e.g., 2, 5, 10, etc.) 16

23 Too flat or too steep? Too flat obscures the message Too exaggerated overstates the trend Note y-axis does not need to start at 0. Why not as bad as in the case of bar chart? 17

24 Rule of Thumb 18

25 Multiple Patterned Lines in one chart 19

26 Better? Note the double encoding of line width and brightness. What if you have many lines you want to show? 20

27 Small Multiple - Edward Tufte Better than overlapping (sometimes) a series or grid of small similar graphics or charts, allowing them to be easily compared 21

28 Tables Name Data Data Data Company A Company B Company C Company D What can you improve? 22

29 What s the problem with making everything bold or italic?

31 When everyone is super, no one will be

32 When everyone is special, no will be! Name Data Data Data Company A Company B Company C Company D

33 Name Data Data Data Data Data Data Company A Company B Company C Company D Company E Company F Company G Company H

Name Data Data Data Data Data Data Company A 0.0 0.0 0.0 0.0 0.0 0.0 Company B 0.0 0.0 0.0 0.0 0.0 0.0 Company C 0.0 0.0 0.0 0.0 0.0 0.0 Company D 0.0 0.0 0.0 0.0 0.0 0.0 Company E 0.

34 Name Data Data Data Data Data Data Company A Company B Company C Company D Company E Company F Company G Company H A lot of chart junk. Low data to ink ratio (Edward Tufte) 26

35 Name Data Data Data Data Data Data Company A Company B Company C Company D Company E Company F Company G Company H Company I Company J Company K Company L Higher data to ink ratio 27

36 Problems? Name Data Name Data Company A 1000 Company B 900 Company C 80 Company D 7 Company A Company B 9.49 Company C 8 Company D

37 Name Data Name Data Company A Company B 9.49 Company C 8 Company D 7.4 Company A 10.8 Company B 9.5 Company C 8.0 Company D

38 Beautiful Publication-quality LaTeX Tables Short guide: Long guide: 30

39 The Dreaded Pie Charts Why people like to use pie charts? 31

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45 Log scale instead of linear scale Include numbers from different orders of magnitude 37

46 Example log-log 38

47 log also works well for time Example The yield curve of Treasury bills, notes and bonds 39

48 In-class Exercise. Applying what you have just learned. 40

49 HEADLINE OF THE CHART A brief description that outlines what the data shows Can you improve its visual design? 41

50 HEADLINE OF THE CHART A brief description that outlines what the data shows Headline of the chart A brief description that outlines what the data shows Town A Town B Town C Town D Which is better? 42

51 How to fix the defaults 43

52 How to fix the defaults 43

53 How to fix the defaults 44

54 How to fix the defaults 44

55 Practitioners Guide Colors: start with black & white, then add colors, carefully Forces you to focus on content and layout Fonts: sans-serif generally easier to read (On Mac: Helvetica is great start) Animation: start with no animation, then add meaningful ones 45

56 Practitioners Guide: Use Pictures and Videos Pictures include tables, diagrams, charts, etc. Pictures often more succinct & memorable People like pictures and love movies And show them ASAP! Once people fall asleep, it s hard to wake them up! If you have good stuff, show them now. 46

57 Example 47

) People skim and look at interesting things first Reviewers are busy and sleepy (read 5-10 papers

58 Practitioners Guide: Additional Tips for Researchers Crown-jewel pictures are important Overview of what readers is going to get cut to the chase (don t tease!) People skim and look at interesting things first Reviewers are busy and sleepy (read 5-10 papers per conference) it s refreshing to read an interesting paper How to do it? Use your most impressive figure Can be similar to another shown later 48

59 Figures should be self-contained Why? Don t make people go back and forth between text & figure Bad figures means bad first impression (reject!) How to fix? Succinctly describe your main (take-away) messages 49

60 Example 50

61 More generally, how to write good papers? Wobbrock-2015.pdf 51

62 Use legible fonts. 52

63 If people can t see it, they won t appreciate it. For printed materials, print them out and check! Rule of thumb: about 7 lines of text on a slide. 53

64 Redesign figures for presentation Designing for print is different from designing for the screen Resolution (which is higher?) Levels of details (people mostly want a few take-away messages from your talk) 54

65 Example 55

66 Example Judges Scores 16 Apolo Scholar Score 8 0 Modelbased *Prototyping *Average Higher is better. Apolo wins. * Statistically significant, by two-tailed t test, p <0.05

67 Great Work destroyed by Poor Presentation Bad color schemes Bad, tiny fonts Too much animation can you read this? 100 times faster! Too much data Don McMillan: Life After Death by PowerPoint 57

Poster and PowerPoint Presentations. Curtis Olson, PhD UW Office of Continuing Professional Development in Medicine and Public Health Rich Path, ICTR

Poster and PowerPoint Presentations Curtis Olson, PhD UW Office of Continuing Professional Development in Medicine and Public Health Rich Path, ICTR Agenda Design principles for PowerPoint slides 45 min