Firm size and effect of R&D on productivity

R&D productivity, calculated from output per worker, capital per worker, R&D expenditure per worker, using a rearranged augmented Cobb-Douglas production function, is regressed against proportion of total R&D expenditures by firms of each size class. Result shows that R&D expenditure by firms with 10-49 employees is the most productive. Data on output, capital, R&D expenditure and labor force come from Eurostat and World Bank.