Technological similarity in national styles of innovation in a historical perspective

The paper examines some issues related to different styles of innovation in some advanced countries. The statistical work carried out is an attempt to answer the question: to what extent do countries' styles of innovation differ and how often similarities arise? The issue of similarity/dissimilarity of countries' styles of innovation is investigated in the last 100 years for a group of selected countries. The evidence provided is based on a US patent database held at the University of Reading and countries' styles of innovation are measured with the use of the RTA index in four historical periods.The conclusions of the paper are consistent with the theory of national systems of innovation. Countries show very different styles of innovation and, what is more important, this difference is stable over time. However, a selected combination of similar countries occurs in every period, thus underlining the existence of regional groups. These regional groups are the only pairs of countries showing technological similarity historically.