PATENTS, RESEARCH-AND-DEVELOPMENT, AND TECHNOLOGICAL SPILLOVERS AT THE FIRM LEVEL - SOME EVIDENCE FROM ECONOMETRIC COUNT MODELS FOR PANEL-DATA

This paper analyses the relationship between the main determinants of technological activity and patent applications. To this end, an origin al panel of 181 international manufacturing firms investing substantia l amounts in R&D during the late 1980s has been constructed. The numbe r of patent applications by firms is explained by current and lagged l evels of R&D expenditures and technological spillovers. Technological and geographical opportunities are also taken into account as addition al determinants. In order to examine this relationship, several econom etric models for count panel data are estimated. These models deal wit h the discrete nature of patents and firm specific unobservables arisi ng from the panel data context. The main findings of the paper are fir st, a high sensitivity of results tb the specification of patent distr ibution. Second, the estimates of the preferred GMM panel data method suggest decreasing returns to scale in technological activity and fina lly a positive impact of technological spillovers on firm's own innova tion. (C) 1997 by John Wiley & Sons, Ltd.