This paper shows how specific technological and relational regimes have shaped the growth of the network of R&D collaborative agreements in pharmaceuticals in the 1990s. Our analysis reveals the existence of a complex set of regimes of firm growth within the network, providing additional...

Complex systems can be characterized by classes of equivalency of their elements defined according to system specific rules. We propose a generalized preferential attachment model to describe the class size distribution. The model postulates preferential growth of the existing classes and the...

We introduce a model of proportional growth to explain the distribution of business firm growth rates. The model predicts that it is exponential in the central part and depicts an asymptotic power-law behavior in the tails with an exponent ζ = 3. Because of data limitations, previous studies in...

We study the betweenness centrality of fractal and non-fractal scale-free network models as well as real networks. We show that the correlation between degree and betweenness centrality C of nodes is much weaker in fractal network models compared to non-fractal models. We also show that nodes of...

This paper compares the innovation performance of established pharmaceutical firms and biotech companies, controlling for differences in the scale and scope of research. We develop a structural model to analyze more than 3,000 drug R&D projects advanced to pre-clinical and clinical trials in the...

We analyze the decline of R&D productivity in pharmaceuticals and its determinants. Since the molecular biology revolution, science has dramatically expanded the set of plausible therapeutic targets. However, innovation has become more difficult to achieve, and attrition rates of R&D projects...

The paper moves a step forward in the direction of establishing a connection between the structure and evolution of knowledge bases and the structure and evolution of organizational forms in innovative activities in a science-intensive industry. The paper has an explicit focus on the dynamics of...

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