Kategorienskala

Kategorienskala, or category scale, is a measurement scale used to classify observations into discrete categories. It refers to qualitative data that take on a limited number of categories. The category scale includes nominal scales, where the categories have no intrinsic order (for example blood type or gender), and ordinal scales, where categories have a meaningful order (for example education level: primary, secondary, tertiary; rating from low to high).

In practice, category scales are used in surveys and data collection to group responses into distinct classes. Nominal data are primarily described by frequencies and proportions, with the mode as a simple measure of central tendency. Ordinal data allow ranking, so the median and nonparametric statistical methods are often appropriate. Arithmetic operations such as calculating a mean are not meaningful for nominal data and are only cautiously applied to ordinal data when treated as having more scale-like properties.

Common examples include Likert-type items (strongly disagree to strongly agree), Likert scales being typically treated as ordinal, and categorical classifications such as marital status or geographic region. When designing a kategorienskala, researchers aim for mutually exclusive and exhaustive categories, reliability in coding, and clarity in category definitions to minimize ambiguity and bias.

Limitations of category scales include the loss of information about magnitude between categories and reduced statistical power compared with interval or ratio scales. Nonetheless, category scales are versatile and widely used in social sciences, market research, and epidemiology for organizing qualitative data and guiding appropriate nonparametric analyses.