Data graphics - CAMP

this map by Charles Joseph Minard portrays the losses suffered by Napoleon's army in the Russian campaign of 1812. Beginning at the Polish-Russian border, the thick band shows the size of the army at each position. The path of Napoleon's retreat from Moscow in the bitterly cold winter is depicted by the dark lower band, which is tied to temperature and time scales

Graphing Design Concepts

Graphical PerceptionSome Considerations

• Some visual processing takes place without any conscious effort on our part

• This is termed preattentive vision.

• Graphical perception derives from preattentive vision to extract information from graphs

• Graphs which convey their information at this unconscious level allow us to extract the information without any considered effort on our part.

Example

Example

Example

Graphing Design Concepts

• To design effective graphs we must know which graphical attributes are most easily decoded.

From Tufte, 2001)

Graphing Design Concepts

• To design effective graphs we must know which graphical attributes are most easily decoded.

Graphical Encodings

• Cleveland and McGill (1984) ranked graphical-perception tasks used to visually extract quantitative information from a graph.

• Angle• Position on common scale• Position on non-aligned scales• Length• Direction • Area• Volume• Curvature• Shading

Area, Angle, Length, Position

Angle + Slope

Shading

Length

Position on Common Scale

Length

Position on Identical but Non-Aligned Scales

Cleveland-McGill Scale

“People’s accuracy in describin the embellished charts was no worse than for plain charts….and their recall after a Two to three week gap was significantly better” (Bateman et al. 2010)