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Small Worlds in Networks of Inventors and the Role of Science: An Analysis of France Francesco Lissoni (1), Patrick Llerena(2), Bulat Sanditov(3) Brescia University & KITeS – Bocconi University, BETA – University of Strasbourg, UNU-MERIT, Maastricht University
Background • Sociology of science: • “Invisible colleges” (De Solla Price 1963, Crane 1972) “Weak links, small worlds and nodes are the most useful words for understanding the way that scientific discovery advances.” (Francis Fukuyama, preface to The New Invisible College by C. Wagner) • Small worlds” & innovation • Theory • Cowan & Jonard (2003, 2004) • Empirical evidence: • Uzzi & Spiro (2005) : Broadway musicals • Schilling & Phelps (2007): Technology alliances • Fleming et al. (2007), Breschi & Lenzi (2011): Co-invention networks
What is this paper about? • Structure of inventors’ networks in France: • Are they “small worlds” (tightly knit communities of inventors & few “shortcuts” between communities)? • Role of academics and CNRS researchers in inventors’ networks • Do they contribute to “small-world” structure (bridging distant communities of inventors)?
Data Sources • EP-INV database (KITeS-Bocconi University) • Patent applications at EPO since 1978 reclassified by applicant and inventor • Subset of inventors with address in France • KEINS database on academic inventors (Lissoni et al. 2006) • Matching inventors with a list of university professors in service in 2004. Verifying matches by contacting professors • Dataset on CNRS inventors (Llerena 2010) • KEINS methodology • CNRS researchers on duty in 2007
Science-intensity by Technological field - Academic & CNRS inventors/patents
Inventors mobility across organizations • Number of distinct applicants normalized by the number of inventor’s patents
NETWORK OF INVENTORS Patents Inventors
Small worlds: Watts & Strogatz (1998) • “Small world” networks: • sparse • clustered • short distances • WS model of SW: Clustering: C = [3 × #(/\)]/ #(/\) Small-world ratio: Q=(Cobs/Сrg)/(Lobs/Lrg)
Benchmark random graph (BRN) • Erdos-Renyi random graph is not an appropriate benchmark random structure for our networks. • An inventor connects with the whole research team (rather than with individual inventors) • Benchmark random graph (BRN): • Keep number of number of inventors per patent and number of patents per inventor, and randomly “rewire” patent-inventor links • Project bipartite graph onto the set of inventors
W-S model for bipartite graph Rewiring starts here Rewiring starts here
Small worlds afterwards? • Small worlds: • Scientific instruments • Chemicals & Materials • Pharmaceutical & Biotech • Industrial processes • Not small worlds: • Electronics & Electrical Eng. • Mech. Eng. & Transport • Consumer goods
Academic &CNRS inventors as small world catalysts: Node-deletion test
Summary • Networks of inventors in France are “small worlds” • In science-intensive technological fields • Shortcuts due to inter-organizational mobility of inventors • Academic and CNRS inventors & “small worlds” • Connect otherwise disconnected components • Bridge between distant communities of inventors shortening distances