Some missing values for the expenditures were estimated using the latest available data and the historical growth rate of investment in a particular country or, where only one estimate was provided, the growth rates for the OECD. Additionally, where no information was provided for private sector R&D expenditures, the R&D expenditure ratio of private to public expenditures between 2001 and 2010 (0.554) was used. Note that this dataset includes R&D expenditure by government and higher education, which would seem to be suitable data to use as public R&D expenditure.