Value of invention , prolific inventor productivity and mobility : evidence from five countries , 1975 - 2002 1

The aim of this paper is to provide new insights into (1) the determinants of the value of inventions and (2) the role that mobility plays in the behavior of prolific inventors, whom we identify based on the number of patents exceeding a threshold of productivity. We examine mobility in two dimensions: from firm to firm (inter-firm) and from one technical field to another. We exploit data on patents filed by inventors from five countries (France, the UK, Germany, the US and Japan) in the US Patent and Trademark office during the period from 1975 to 2002. From our regressions we obtain a rich set of results. In particular we show that: (1) as predicted by evolutionary theory, inventor productivity is a positive determinant of invention value, (2) inter-firm mobility is a consistently positive determinant of productivity and (3) technological mobility is a negative determinant. The last implies that the more specialized an inventor is, the higher his productivity is.