The R&D/GDP ratio discussed above can be used to determine the relative emphasis placed on R&D activities by the United States and other countries. Another useful measure is to compare the number
of R&D scientists and engineers in a country with its total labor force. Use of these ratios bypasses many of the problems in interpretation caused by inflation, exchange rate fluctuations, different unit costs, and variations in the volume of
research efforts. Caution must nonetheless be exercised in making even these international comparisons, because each country compiles its R&D and personnel data somewhat differently.