Nominal number

A feature scaled nominal ( from the Latin noun " name " from the Greek onoma, Pl: nouns, also noun ) if its possible forms can be distinguished, but not have a natural ranking. A nominal skalierendes feature is made ​​measurable by a description of categories, after each examination unit ( exactly ) can be assigned to a category. The result of such operationalization is then called a nominal scale. Because of the lack of order here - scale is (from Latin Scalae, ladder, stairway ') really is not appropriate and should be seen in context with the other levels of scale.

Formal conditions

The formal terms of a nominal scale are:

Examples

Examples of nominal scaled characteristics of a human:

• Gender: Male, Female
• Place of birth: Hamburg, Berlin, Heidenheim
• Religious affiliation: Protestant, Catholic, Muslim

Possible operations and transformations

The only structure-preserving transformations are renaming, by the words of each category is one-one, a new category. Therefore, even if the categories can be coded by numbers ( this is called nominal numbers, example: Job 1, Job 2, ...), are mathematical operations with these codes, eg a division "Carpenter / baker ", does not make sense. Likewise, size comparisons using nominal scaled features not useful. Sense, however, the determination of occurrence frequencies of the categories in a set of inspection units which are then subject of the statistics. As a location parameter such frequency distribution can be determined only the most frequent value, called the modal value.