engangseffekter

Engangseffekter, meaning one-off effects, are effects that occur at a single point in time or during the initial phase of an intervention and are not expected to recur with subsequent exposure. The term is used in Norwegian and Swedish contexts and is often contrasted with recurring, persistent, or long-term effects.

These effects arise when an action triggers a temporary change that is not repeated as the system settles or as behavior adapts. Examples can be found in different fields: in public policy, one-off start-up costs or transitional benefits; in environmental management, an initial release of sediment following construction or a temporary disturbance; in economics, a one-time financial gain or cost associated with a policy change; and in medicine, immediate reactions that occur upon first exposure but do not persist with ongoing treatment.

Assessment of engangseffekter typically involves defining a clear time horizon and a baseline, identifying the one-off component separately from ongoing impacts. They are often presented as discrete line items in cost-benefit analyses or impact assessments to avoid conflating short-term, non-recurring effects with long-term outcomes. The treatment of these effects can influence decision-making, especially when evaluating the overall desirability or affordability of an intervention.

Limitations include the potential for one-off effects to have lasting indirect consequences or to interact with subsequent, recurring impacts in complex ways. Attribution can be challenging, and misclassifying a long-term effect as one-off can mislead policy or budgeting.

Related concepts include non-recurring costs, initial impacts, and first-dose or initial effects in various applied contexts.