Choices in How We Make Representations - A Primer of GIS: Fundamental Geographic and Cartographic Concepts - page 37

Stevens developed his reference scheme in the 1940s. His intent was to
offer a framework for psychologists and other social sciences that could take
intrinsic properties into consideration. Extrinsic properties are those that are
directly empirically measurable: width, height, depth, elevation, and the like.
Intrinsic properties are characteristics that can be observed, but must be associ-
ated with other properties—for example, color, age, form, quality. Extrinsic
properties can be established directly from an object, but intrinsic properties
must be indirectly measured, inferred, or interpreted.
Because of the nature of intrinsic properties, Stevens proposed that
measurements should be distinguished according to the ability to combine
them with other measurements. For example, the measurement of a per-
son's height cannot be meaningful combined with the measurement of his or
her hair color. Following Stevens, height is an interval measure and color is a
nominal value.
In all, Stevens differentiates four types of measurement, which unfortu-
nately are not exhaustive and fail to include common types of geographical
information such as radial measures of angles. The four measurements and
their definitions are:

Nominal Qualitative measurements (name, type, state)

Ordinal Quantitative measurements with a clear order, but

without a defined 0 value (small, medium, large)

Interval Quantitative measurements with a defined beginning

point (temperature, height, distance)

Ratio Quantitative measurements that provide a relation-

ship between two properties where the 0 value indi-
cates the absence of the relationship (particulates
mg/m 3 , time to cover a distance, dissolved oxygen in
a liter of water)

Sinton's Framework

Applying Stevens's measurement framework to manual cartography was rela-
tively straightforward because of an individual's (or organization's) control
of the design and drawing process. The use of computers and sharing of geo-
graphic information changed this because now data collection management
and output are divided between numerous individuals and organizations.
During the early days of GIS, a number of people working in this area real-
ized that the established “art and science” of the cartographer required
more detailed descriptions of cartographers' and geographers' work if peo-
ple were ever to successfully automate cartography, especially if maps were
to be used as the basis for analysis. “Analytical cartography,” as it is called,
produced a number of important approaches and concepts that became crit-