Additionality is a notional measurement of an intervention (i.e., doing something), when the intervention is compared to a baseline, status quo metric (i.e., doing nothing). The 'intervention' can be based on either technology or economics. For an example of a technology based intervention, see the use of the word when discussing carbon credits.
Economic additionality is a relatively new concept, and a working definition of the term is shown below:
Net positive difference that results from economic development intervention. The extent to which an activity (and associated outputs, outcomes and impacts) is larger in scale, at a higher quality, takes place quicker, takes place at a different location, or takes place at all as a result of intervention. Additionality measures the net result, taking account of deadweight, leakage, displacement, substitution and economic multipliers.
Additionality is calculated by the following formula:
A = Iin − Irc
where A is the additionality, Iin is the impact of the intervention, and Irc is the impact of a reference case.
- "Additionality". Retrieved 21 July 2012.
- Appraisal & Evaluation Team. "Additionality & Economic Impact Assessment Guidance Note: A Summary Guide to Assessing the Additional Benefit, or Additionality, of an Economic Development Project or Programme". Scottish Enterprise. Retrieved 21 July 2012.
- "Additionality Guide: A Standard Approach to Assessing the Additional Impact of Projects". English Partnerships. Retrieved 21 July 2012.