visualizing data

Visualizing DataJeff Arnold

April 9, 2013Emory University, Atlanta

Data Viz is EverywhereBusiness / EconomicsWeatherSportsFinance

OutlineExamples1.  Florence Nightingale2.  Challenger ExplosionWhat is it?How does it work?When doesn't it work?

Examples

Florence Nightingale

Challenger Explosion

What is DataVisualization?

Grammar of Graphics

Grammar of Graphics

Grammar of GraphicsGeometric Shapespointslinesbarstext

Aesthetics: convey informationx positiony positionsize of elementsshape of elementscolor of elements

Data and Aesthetics

How does itwork?

PATTERNSPATTERNSPATTRESNPATTERNS

Anscombe Quartet

Looking for Patterns

Expected DataActual DataPlots are Comparisons

When (and why)does it not

work?1.  Too many variables2.  Too many observations3.  Perceptual biases4.  Understanding randomness

Too Many Variables

Too Many Observations (I)

Too Many Observations (II)

Too Many Observations (III)

Visual Perception BiasesQ: What is the value of a ­ b? Does it change?

Visual Perception BiasesA: a ­ b = 2 everywhere.

Visual Perception Biases

Visual Perception Biases

Understanding RandomnessQ: In which plot were the points selected from a uniform

random distribution?

Understanding RandomnessA: The plot on the right. 

ConclusionData visualization and statistics are complementary

Data visualizationintuitivecognitive biases

Statistical methodsun­intuitiveovercome our cognitive biases

Questions?

References

Kimmo Soramaki, Morten L. Bech, Jeffrey Arnold, Robert J. Glass and Walter E. Beyeler (2007). "The Topology of

Interbank Payment Flows", Physica A. 

Hadley Wickham (2010). "A Layered Grammar of Graphics", Journal of Computational and Graphical Statistics. 

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

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