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The Green Lab - [11-A] Data Visualization

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This presentation is about a lecture I gave within the "Green Lab" course of the Computer Science master, Software Engineering and Green IT track of the Vrije Universiteit Amsterdam: http://masters.vu.nl/en/programmes/computer-science-software-engineering-green-it/index.aspx
http://www.procaccianti.me

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The Green Lab - [11-A] Data Visualization

  1. 1. 1 Het begint met een idee Data Visualization Giuseppe Procaccianti
  2. 2. Vrije Universiteit Amsterdam 2 Giuseppe Procaccianti / S2 group / The Green Lab Quick Recap: Experimental Process Experiment scoping Experiment planning Idea Experiment operation Analysis & interpretation Presentation & package
  3. 3. Vrije Universiteit Amsterdam 3 Giuseppe Procaccianti / S2 group / The Green Lab What is Data Visualization? «The use of computer-supported, interactive, visual representations of abstract data to amplify cognition». Readings in Information Visualization: Using Vision to Think. S.K.Card, J.D.Mackinlay, and B.Shneiderman, Academic Press, 1999
  4. 4. Vrije Universiteit Amsterdam 4 Giuseppe Procaccianti / S2 group / The Green Lab Examples of amplified cognition
  5. 5. Vrije Universiteit Amsterdam 5 Giuseppe Procaccianti / S2 group / The Green Lab More examples of amplified cognition WTF Visualizations: http://viz.wtf/
  6. 6. Vrije Universiteit Amsterdam 6 Giuseppe Procaccianti / S2 group / The Green Lab Data visualization: science or art?
  7. 7. Vrije Universiteit Amsterdam 7 Giuseppe Procaccianti / S2 group / The Green Lab Data visualization theory Quantitative communication
  8. 8. Vrije Universiteit Amsterdam 8 Giuseppe Procaccianti / S2 group / The Green Lab Quantitative communication Quantitative values (measures) Categorical information (groups)
  9. 9. Vrije Universiteit Amsterdam 9 Giuseppe Procaccianti / S2 group / The Green Lab Quantitative communication: example Categorical information (name) Categorical information (group) Quantitative values
  10. 10. Vrije Universiteit Amsterdam 10 Giuseppe Procaccianti / S2 group / The Green Lab Quantitative communication: example Both Categorical Quantitative
  11. 11. Vrije Universiteit Amsterdam 11 Giuseppe Procaccianti / S2 group / The Green Lab Tables vs. graphs Tables ● Easy look-up of values (comparisons) ● Precise values ● Different units of measure are possible Graphs ● Overall "shape" of data (trends) ● Reveal relationships between multiple variables
  12. 12. Vrije Universiteit Amsterdam 12 Giuseppe Procaccianti / S2 group / The Green Lab Data visualization theory Graphical Integrity
  13. 13. Vrije Universiteit Amsterdam 13 Giuseppe Procaccianti / S2 group / The Green Lab Graphical integrity [1] ● Data visualization must tell the truth [1] Edward R. Tufte, 1983. The Visual Display of Quantitative Information. Graphics Press. ● Avoid misleading information and chartjunk
  14. 14. Vrije Universiteit Amsterdam 14 Giuseppe Procaccianti / S2 group / The Green Lab Graphical integrity: principles ● Proportionality ● Utility ● Clarity
  15. 15. Vrije Universiteit Amsterdam 15 Giuseppe Procaccianti / S2 group / The Green Lab Proportionality: Lie Factor ● Ideal LF = 1 ○ if LF > 1 you are overstating an effect ○ if LF < 1 you are understating an effect
  16. 16. Vrije Universiteit Amsterdam 16 Giuseppe Procaccianti / S2 group / The Green Lab Proportionality: Lie Factor Data Visualization 5.3/0.6 = 8.83 27.5/18 = 1.53 LF=5.77
  17. 17. Vrije Universiteit Amsterdam 17 Giuseppe Procaccianti / S2 group / The Green Lab Utility: data ink ● Ideal Data-Ink ratio != 1 ○ a balance must be found between readability and utility
  18. 18. Vrije Universiteit Amsterdam 18 Giuseppe Procaccianti / S2 group / The Green Lab Utility: data ink
  19. 19. Vrije Universiteit Amsterdam 19 Giuseppe Procaccianti / S2 group / The Green Lab Utility: data ink
  20. 20. Vrije Universiteit Amsterdam 20 Giuseppe Procaccianti / S2 group / The Green Lab Clarity
  21. 21. Vrije Universiteit Amsterdam 21 Giuseppe Procaccianti / S2 group / The Green Lab Clarity
  22. 22. Vrije Universiteit Amsterdam 22 Giuseppe Procaccianti / S2 group / The Green Lab Data visualization theory Information Encoding
  23. 23. Vrije Universiteit Amsterdam 23 Giuseppe Procaccianti / S2 group / The Green Lab How to encode information in a graph ● Quantitative information ○ Points: relative position ○ Lines: relative position, slope, length ○ Bars: length (height) ○ (2D) shapes: area
  24. 24. Vrije Universiteit Amsterdam 24 Giuseppe Procaccianti / S2 group / The Green Lab Points
  25. 25. Vrije Universiteit Amsterdam 25 Giuseppe Procaccianti / S2 group / The Green Lab Lines
  26. 26. Vrije Universiteit Amsterdam 26 Giuseppe Procaccianti / S2 group / The Green Lab Lines
  27. 27. Vrije Universiteit Amsterdam 27 Giuseppe Procaccianti / S2 group / The Green Lab Bars Width plays no role! Zero-based scale (LF)
  28. 28. Vrije Universiteit Amsterdam 28 Giuseppe Procaccianti / S2 group / The Green Lab Columns
  29. 29. Vrije Universiteit Amsterdam 29 Giuseppe Procaccianti / S2 group / The Green Lab 2D shapes (the infamous pie chart) Always put percentages!
  30. 30. Vrije Universiteit Amsterdam 30 Giuseppe Procaccianti / S2 group / The Green Lab 2D shapes (the infamous pie chart)
  31. 31. Vrije Universiteit Amsterdam 31 Giuseppe Procaccianti / S2 group / The Green Lab How to encode information in a graph ● Categorical information ○ Position (along an axis) ○ Color ○ Shape ○ Fill ○ Linestyle
  32. 32. Vrije Universiteit Amsterdam 32 Giuseppe Procaccianti / S2 group / The Green Lab Position, color
  33. 33. Vrije Universiteit Amsterdam 33 Giuseppe Procaccianti / S2 group / The Green Lab Shape
  34. 34. Vrije Universiteit Amsterdam 34 Giuseppe Procaccianti / S2 group / The Green Lab Next lab session: ggplot tutorial ● R advanced graphics package ● https://cran.r-project.org/web/packages/ggplot2/index.html ● REMINDER: Wednesday 9am!!
  35. 35. Vrije Universiteit Amsterdam 35 Giuseppe Procaccianti / S2 group / The Green Lab References and further readings ● Graph design principles, M. Torchiano (slides) on BB ● Edward R. Tufte, 1983. The Visual Display of Quantitative Information. Graphics Press. ● Manuel Lima: A visual history of human knowledge
  36. 36. Vrije Universiteit Amsterdam 36 Giuseppe Procaccianti / S2 group / The Green Lab Thank you! g.procaccianti@vu.nl i.malavolta@vu.nl

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