Absolute scale

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There is no single definition of an absolute scale. In statistics and measurement theory, it is simply a ratio scale in which the unit of measurement is fixed, and values are obtained by counting.^[1] Another definition tells us it is the count of the elements in a set, with its natural origin being zero, the empty set.^[2] Some sources tell us that even time can be measured in an absolute scale, proving year zero is measured from the beginning of the universe.^[3] Colloquially, the Kelvin temperature scale, where absolute zero is the temperature at which molecular energy is at a minimum, and the Rankine temperature scale are also referred to as absolute scales. In that case, an absolute scale is a system of measurement that begins at a minimum, or zero point, and progresses in only one direction.^[4] Measurement theory, however, categorizes them as ratio scales. In general, an absolute scale differs from a relative scale in having some reference point that is not arbitrarily selected.