Le rendement social des activités de RαD en France. Mesure, évolution, différenciation industrielle

In this paper we evaluate the private and social rates of return of R?D activities for 21 French manufacturing industries over a 10 years period (1985-1995). We use a well-known methodology mainly based on input-output matrixes to which we add results regarding the innovatory use of capital goods from the French innovation survey. Our findings globally confirm the results of other studies for other countries. They indicate that the private rate of return is much smaller than the social rate and is weakly significant over the 10 years period. The explanation seems to be twofold. First of all there is certain variability across time. The private rate of return of R?D activities increases rapidly from the mid-80?s to the early 90?s. The increase in the rate of intra-sectoral diffusion of innovation explains this phenomenon. Secondly a dual effect seems to appear concerning the relative size of the stock of external R?D. Industrial sectors with a large stock of external R?D compared to their stock of own R?D have a private rate of return near zero and the impact of their indirect R?D is positive and significant. The inverse is true for industrial sectors with a small external stock of R?D which finally constitutes a very important share of the overall bulk of R?D expenditures. Only four sectors are strongly dependent on external technology. Classification JEL : L16, 03, 04, 05