Talk I gave on April 9, 2013 for a post-doc position. Intended to be a lecture from an undergraduate level political science introductory statistics course.

1. Visualizing Data
Jeff Arnold
April 9, 2013
Emory University, Atlanta

2. Data Viz is Everywhere
Business / Economics
Weather
Sports
Finance

3. Outline
Examples
1. Florence Nightingale
2. Challenger Explosion
What is it?
How does it work?
When doesn't it work?

4. Examples

5. Florence Nightingale

8. Challenger Explosion

11. What is Data
Visualization?

12. Grammar of Graphics

13. Grammar of Graphics

14. Grammar of Graphics
Geometric Shapes
points
lines
bars
text
Aesthetics: convey information
x position
y position
size of elements
shape of elements
color of elements

15. Data and Aesthetics

16. How does it
work?
PATTERNS
PATTERNS
PATTRESN
PATTERNS

17. Anscombe Quartet

18. Looking for Patterns

19. Plots are Comparisons
Actual Data Expected Data

20. When (and why)
does it not
work?
1. Too many variables
2. Too many observations
3. Perceptual biases
4. Understanding randomness

21. Too Many Variables

22. Too Many Observations (I)

23. Too Many Observations (II)

24. Too Many Observations (III)

25. Visual Perception Biases
Q: What is the value of a ­ b? Does it change?

26. Visual Perception Biases
A: a ­ b = 2 everywhere.

27. Visual Perception Biases

28. Visual Perception Biases

29. Understanding Randomness
Q: In which plot were the points selected from a uniform
random distribution?

30. Understanding Randomness
A: The plot on the right.

31. Conclusion
Data visualization and statistics are complementary
Data visualization
intuitive
cognitive biases
Statistical methods
un­intuitive
overcome our cognitive biases

32. Questions?

33. References
Nightingale receiving the Wounded at Scutari, By Jerry Barrett
Diagram of the Causes of Mortality in the Army in the East, by Florence Nightingale
Space Shuttle Challenger explodes shortly after take­off.
Plot of GE vs. SP500 from Yahoo! Finance
Kimmo Soramaki, Morten L. Bech, Jeffrey Arnold, Robert J. Glass and Walter E. Beyeler (2007). "The Topology of
url
Interbank Payment Flows", Physica A.
url
Hadley Wickham (2010). "A Layered Grammar of Graphics", Journal of Computational and Graphical Statistics.