An empirical analysis of endogenous growth without scale effect

The aim of this paper is to empirically examine the endogenous growth without scale effect as in Segestrom (1998). We firstly build a concordance table between the 1972 Standard Industrial Classification System (SIC) and USPCS (as of December, 31 2002) industrial codes using the USPTO concordance new file. Then we approach the analysis of the difficulty index of each industry starting from the NBER patent data set (63_99) using the mean forward citations lag data as the fundamental variable of our analysis. In fact we follow the idea that each patent number of citations grows untill a point from which it starts to decade. We explain that point as the moment that draws the obsolescence of the invention. Once we have eliminated by that way the lag truncations problem we obtain the difficult index serie of each industrial sector. Finally we describe the relationship between the growth of the difficulty index and the number of scientists and engeneers. Our investigation concludes showing a difference between traditional and new sectors where in the latters the absence of the scale effect is more clear than in the others.