Choosing Symbols
Reading in Slocum: Chapter 4

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

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

Visual variables:
    • for qualitative differences (nominal, categories):
        hue, shape, arrangement, orientation
    • for ordering (hierarchy; ordinal, numerical):
        lightness, size, spacing, saturation, height

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

see Fig. 4.3 and Color Plate 4.2

What are characteristics of example maps?
Area examples: choropleth, proportional symbols, isopleth, dot map

Ordered: