tidsviktat

Tidsviktat is a term used to describe values or measurements that are weighted according to the time each value is applicable. In statistics and applied sciences, time weighting provides a more accurate representation of a variable that changes over time by accounting for how long each observed value persists.

Calculation is straightforward in discrete form: if c_i is the value observed for a duration Δt_i within a total period T = sum Δt_i, the time-weighted average is TWA = (1/T) × Σ(c_i × Δt_i). If the variable is continuous, the time-weighted average is written as TWA = (1/T) × ∫ c(t) dt over the period. The concept can also be applied with other time-based weighting schemes, depending on the context.

Tidsviktat differs from a simple arithmetic mean, which gives equal weight to all observations regardless of how long they apply, and from frequency-based weighting that emphasizes occurrences rather than duration. In practice, the idea appears in various fields under several related terms, such as time-weighted exposure or time-weighted return in finance, depending on the domain and convention.

Applications of tidsviktat include assessing occupational exposure to chemicals over a work shift, describing average drug exposure in pharmacokinetics over a dosing interval, and summarizing fluctuating environmental concentrations in risk assessments. The term is commonly found in Swedish-language texts, with the equivalent English concept typically described as time-weighted or time-weighted average.