mittelineaarinen

Mittelineaarinen is a Finnish term used in mathematics, statistics, and measurement theory to describe a form of linearity that concerns measurement scales. The word is formed from mitta (measure) and lineaarinen (linear). In Finnish technical writing it is typically used to indicate that a relationship or model is linear with respect to a particular measurement unit or scale, while allowing nonlinear behavior with respect to other dimensions.

Practically, mittelineaarinen models or relationships appear in contexts such as partially linear modeling, where the response is expressed as a linear function of a measured quantity combined with nonlinear terms in other variables. The exact interpretation of mittelineaarisuus can vary by author or field, and there is no single universal formal definition in Finnish literature.

Because it is a descriptive label rather than a formal mathematical category, the term is most common in Finnish-language textbooks and articles dealing with measurement and scale effects, data transformation, or model specification on different measurement levels.

Related terms in Finnish include lineaarinen (linear) and osittain lineaarinen (partially linear). In English-language sources, the closest general notions are linearity with respect to measurement scales or partially linear models, depending on context.