When comparing total business research and development (R&D) intensity (R&D expenditure relative to value added or gross domestic product) across countries it is important to take into account differences in their industrial structure. While there is significant variation in R&D intensity within sectors, some sector-specific patterns make it very difficult for a country to raise its R&D intensity significantly without fundamentally changing its industrial structure. An understanding of the extent to which structural differences can account for observed differences in overall business R&D intensity can be achieved by constructing an indicator that shows what a country’s total R&D intensity would be if it had the same industrial structure as the average for OECD countries.