TABLE OF CONTENTS Measurement has been one of the major contributors to the evolution of civilization.
All measurement is comparison.
Measurement represents the characteristics of the referent by means of symbols. Investigation of symbol system types leads to identification of measurement scale types.
There are five main measurement scale types: nominal, ordinal, interval, ratio and absolute. These are the most common types of scales, but many others have been developed for special purposes. Understanding the scale types and choosing appropriate symbol systems helps to ensure correct interpretation of measurement values.
The nominal scale represents the value of an attribute by any symbol taken from a predefined symbol set, possible options including colour codes and shapes. This type of scale is used to identity referents of matching attribute value, and the measurement can be carried out without instrumentation. The only relation pair applicable in the nominal scale is equal to and not equal to . Scaling transformation amounts to mapping one symbol set into another.
The ordinal scale is used in ranking. It employs two relation pairs, adding greater_than and its converse, less_than, to the pair used in the nominal scale. Its symbol system need not be numerical but must comprise an ordered set of symbols, alphabets offering a favoured choice. This type of measurement can usually be carried out without instrumentation, such as by a sequence of simple pairwise comparisons. Scaling transformation amounts to mapping one ordered symbol set into another.
The interval scale uses the concept of distance between measured values.
