Additionality can take several forms, and each calls for a different outcome measure.
Scale. The supported project may be larger than the feasible unassisted alternative. The relevant comparison is incremental capacity or investment, with common prices and scope. A rise in project cost caused by higher construction prices is not evidence of a larger real investment response.
Timing. Support may bring an investment forward. The evaluation should compare the full investment paths, including any later period in which the unsupported project would have caught up. Reporting only the early gain can overstate the long-run addition, although earlier availability can still have economic value.
Location. A project may move between jurisdictions. The host can gain employment, supplier demand, or strategic capacity without a corresponding increase in global production. The report should state whose outcome is being evaluated and examine the displaced location when making broader claims.
Technology or quality. A firm may choose equipment with lower emissions, higher efficiency, or different capabilities. Capital spending alone may fail to measure the intended change. The evaluator needs a specified technical benchmark and evidence of operation, with the unassisted technology treated as a real alternative.
Knowledge or coordination. A program may support learning, shared infrastructure, or collaboration that benefits other firms. Counting meetings, agreements, or participation establishes activity. Demonstrating an economic effect requires evidence that the collaboration changed capability, cost, adoption, or another defined outcome.
These margins need not be combined into one score. A program can succeed in accelerating a project while failing to increase its eventual scale. It can generate useful knowledge without producing a commercially successful plant. Reporting the separate results is more informative than choosing the one favorable indicator and presenting it as proof of overall effectiveness.