In her last post, Katharina pointed to a great data source on R&D expenditure, GERD. In the comment section of that post we discussed the issue of cuts in government R&D expenditures. An interesting question in this context is whether public R&D expenditure is a complement to private R&D expenditure or a substitute. If it is a complement, cuts in the public R&D budget are very bad, because they can be expected to be followed by cuts in private research budgets. If it is a substitute, public R&D ‘crowds out’ private R&D, so that public cuts are not that bad because they can be expected to be replaced by private R&D.
There is an extensive literature on this question, yielding mixed results. So I asked myself what does GERD say? The figure below shows a scatterplot of government and private expenditure on R&D as a share in GDP for 36 countries in 2008. You can see that the data points are pretty much all over the place (Austria is marked red). It turns out that if you regress private on public R&D expenditure, you get a positive coefficient indicating complementarity. However, the coefficient is not statistically significant (t-ratio of 1.63) and the R-squared is very low. So we have no strong evidence for complementarity, but also no evidence for substitutability. Instead, what my recreational econometrics exercise suggests is that private R&D expenditure is pretty much independent from government research budgets.