Measurement, value, and scale.
The terms 'qualitative', 'semiquantitative', and 'quantitative' are used ambiguously. Based on international recommendations by IEC, IFCC, ISO, IUPAC, and OIML, and the work on scales by Stevens, a systematic terminology is presented. Measurement is considered to be the set of operations by which a value (consisting of a relational operator, and symbols, figures, or letters) is assigned to a quantity. The possible values constitute a scale that may be subdivided into classes. A hierarchy of four types of scale is characterized: nominal (values are independent of magnitude), ordinal (ranked according to magnitude), interval (equality of differences, arbitrary zero), and ratio scale (equality of ratios, absolute zero); each type allows a different set of statistical calculations. The type of scale is independent of its number of values or classes, or the uncertainty of measurement. The number of values on a scale is indicated by the terms two-value, three-value,..., multivalue and the number of classes analogously by two-class, etc. Examples of transformation of quantities are given.
Department of Clinical Chemistry, Frederiksberg Hospital, Denmark.
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Jørgensen
D002623:Chemistry Techniques, Analytical / Q000379:methods* / Q000592:standards; D002624:Chemistry, Clinical / Q000379:methods* / Q000592:standards; D006801:Humans