scale

Definition:
In brief there are four types of scale: nominal, ordinal, interval and ratio, and their properties may be summarized as: (a) Nominal scales This is the weakest form of scale in which the number assigned serves only to identify the subjects under consideration Library classification schemes employ nominal scales, as does the Standard Industrial Classification (SIC) such that members of the same class will be assigned the same number but each class will have a different number By extending the number it is possible to achieve finer and finer distinctions, until a unique number is assigned to a specific object, eg a telephone number (b) Ordinal scales seek to impose more structure on objects by rank ordering them in terms of some property which they possess such as height or weight. As with nominal scales, identical objects are given the same number but the ordinal scale has the added property that it can tell us something about the direction or relative standing of one object to another, e.g. 1 may represent the smallest member of a group such that we can safely say that 2 is bigger than 1, 5 is bigger than 2 and 17 is bigger than 5. However, this is all we can say (other than reversing the scale) and in order to be able to draw conclusions about differences between the numbers we must know something about the interval between the numbers. (c) Interval scales have this property in that they are founded on the assumption of equal intervals between numbers, i.e. the space between 5 and 10 is the same as the space between 45 and 50 and in both cases this distance is five times as great as that between 1 and 2 or 11 and 12 etc. However, it must be stressed that while we may compare the magnitude of the differences between numbers we cannot make statements about them unless the scale possesses an absolute zero, in which case we would have a ratio scale. (d) Ratio scales are the most powerful and possess all the properties of nominal, ordinal and interval scales, while in addition they permit absolute comparisons of the objects e.g. 6 metres is twice as high as 3 metres and six times as high as 1 metre. Amongst the more important scaling techniques borrowed by marketers from the behavioural sciences may be distinguished: THURSTONE'S COMPARATIVE JUDGEMENT TECHNIQUE, LIKERT SCALES, GUTTMAN SCALES, SEMANTIC DIFFERENTIAL.

Cross-References:
[Thurstone scales] [Likert scales] [Guttman scales] [semantic differential]

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