Measuring the returns of R&D—An empirical study of the German manufacturing sector over 45 years

Motivated by recent statistics that show significant growth in labor productivity, this paper seeks to analyze the long-term relationship between domestic R&D, knowledge stock and productivity dynamics. Time series data of the German manufacturing industry is used to estimate a variable cost function with the stock of knowledge being dependent upon current and past R&D spending. The estimates indicate that 50% of the effects of R&D on the knowledge stock appear within 4 years. However, the rate of return on R&D are shown to be drastically declining; recent rates of return on R&D are estimated to have reached an all-time low spanning the last 45 years. Current yields of R&D are only one third compared to the sixties. In conclusion, though the productivity slowdown of the seventies seems to have been overcome, this is not attributed to R&D investments.