What Difference Does it Make? Additionality in the Public Support of R&D in Large Firms

The concept of additionality has been widely used in rationalizing public support for R&D. In simplest terms, it measures the extent to which public support stimulates new R&D activity as opposed to subsidising what would have taken place anyway. To be used effectively as a policy instrument, however, additionality should encompass not just the direct but the behavioural effects of government support. Also, for large firms in particular, additionality should be viewed in the context of the R&D project portfolio and of corporate technology strategy.