Abstract:
International differences in economic performance are often attributed to differences in innovative performance. Much empirical work supports this contention, but problems in quantifying innovative output prevent researchers from drawing a clear picture. Innovations are very heterogeneous regarding their importance, with only very few innovations yielding substantial returns. Citation frequencies are one measure of the value of innovations. We use a recently introduced technique based on results from Extreme Value Theory to estimate the characteristics of the tail of the distribution of citations. We identify important innovations as those that receive a number of citations higher than the ‘cutoff point’ of the tail of the distributions of citations. The data come from the NBER Patent-Citations Database. We provide estimates of the proportions of important patents for 31 technological categories and discuss emerging patterns. Possible implications for technology policy and innovation management are also drawn.