Breadth and Depth of Main Technology Fields: An empirical investigation using patent data

Recently work on technological change has emphasized the importance and implications of different knowledge bases among industries in terms of innovative potential. In some industries, products and processes have become more complex, as well as there appears to be increased convergence in some market segments. Although increasing attention has been given to features of knowledge bases, there have been limited empirical research on how to measure them. In this paper a method is proposed to measure empirically the breadth and depth dimensions of main technology fields, sectors and firms in the economy. For this purpose, we measure the knowledge bases of 30 main technology fields by using the concepts of breadth and depth. Breadth corresponds to the range of different subjects that a technology field draws upon. Depth refers to the extent to which a certain field is exploited in detail. We position the main technology fields in the breadth and depth space by utilizing the EPO (European Patent Office) database between 1978-2000. We also present the evolution of breadth and depth through time, as well as the breadth and depth dimensions of 40 largest firms in biotechnology and telecommunications. Our results reveal that the both technology fields and firms are largely scattered in the breadth and depth space. Biotechnology stands out to have the highest breadth and depth.