Choosing Symbols
Reading in Slocum et al.: Chapter 5

Phenomena:
    • point, line, area, volume
    • discrete ––> continuous
    • smooth ––> abrupt (stepped)

Levels of measurement:
    • nominal
    • ordinal, interval, ratio

Visual variables:
    • for qualitative differences (related terms: nominal, categorical):
        hue, shape, arrangement, orientation
    • for quantitative (related terms: hierarchy, ordered, numerical):
        lightness, size, spacing, saturation, height

Spatial dimension:
    • symbols emphasizing points, lines, area, 2½D, 3D

(Spatial dimension of phenomenon and symbol not always matched)

See Fig. 5.3 and 5.4 and Color Plate 5.2 and 5.3 in Slocum text

What are characteristics of example maps?

Area examples: choropleth, proportional symbols, isopleth, dot map

Ordered: