Epääyksiköillä

Epääyksiköillä is a Finnish term used in scientific and technical contexts to describe quantities that are represented without a conventional unit. The form combines epä- (not) with yksikkö (unit) and the plural instrumental suffix -illä, indicating “with non-units” or “in unitless form.” In practice, such expressions refer to values that do not carry a specific measurement unit because units cancel out, because the quantity is a ratio, or because the value has been normalized or standardized.

Dimensionless quantities are the primary examples of epäyksiköillä. These include pure numbers that describe ratios or constants where no unit remains after simplification. Examples are mathematical constants like pi or the square root of two, as well as physical quantities that are inherently unitless in practice, such as certain coefficients of proportionality, aspect ratios, or normalized indicators. In statistics and data analysis, many results are unitless as well, such as z-scores, correlation coefficients, and p-values, which are interpreted without reference to physical units.

Use and interpretation in Finnish writing often emphasize that a result is in epäyksiköillä to convey that the value should be understood as a relative, comparative, or scale-free quantity rather than a measurement with a physical unit. This can aid comparability across systems or datasets but may require clarification about what is being compared, and whether any hidden units or reference scales still apply.

See also: dimensionless quantity, unit, normalization, SI units, unit analysis.