koppelingsindex

Koppelingsindex, or coupling index, is a term used in Dutch-language literature to denote a quantitative measure of the strength of the connection or interaction between two elements within a system. The exact definition varies by field, and there is no single universal formula.

In general, the index attempts to capture how strongly one element influences another or how tightly related two variables are. Common formulations include correlation-based measures (such as Pearson or Spearman correlations), information-theoretic measures (such as mutual information and normalized mutual information), and domain-specific indices developed for particular systems. The index is typically presented as a dimensionless value, often scaled to between 0 and 1, though some definitions allow negative or values outside this range depending on the method.

Calculation depends on context: with data, one constructs a measure from paired observations, possibly incorporating time lags for dynamic coupling; in models, it may be derived from coupling terms or energy exchange between subsystems. The choice of method depends on whether the relationship is expected to be linear, nonlinear, or directional.

Applications span disciplines such as physics and engineering (mechanical or energetic coupling), chemistry and materials science (interaction strength between components), and statistics or econometrics (degree of dependence between variables), as well as network analysis to quantify link strength between nodes.

See also: koppeling, koppelingsconstante, cross-correlation, mutual information, correlation coefficient.