title: Law of corresponding states for open collaborations.
abstract: We study the relation between number of contributors and product size in Wikipedia and GitHub. In contrast to traditional production, this is strongly probabilistic, but is characterized by two quantitative nonlinear laws: a power-law bound to product size for increasing number of contributors, and the universal collapse of rescaled distributions. A variant of the random-energy model shows that both laws are due to the heterogeneity of contributors, and displays an intriguing finite-size scaling property with no equivalent in standard systems. The analysis uncovers the right intensive densities, enabling the comparison of projects with different numbers of contributors on equal grounds. We use this property to expose the detrimental effects of conflicting interactions in Wikipedia.
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, UMR 7238, Computational and Quantitative Biology, 15 rue de l'École de Médecine Paris, France.|Dipartimento di Fisica, Università degli Studi di Milano, via Celoria 16, 20133 Milano, Italy.|I.N.F.N. Milano.
authors.forename: Marco
authors.initials: M
authors.lastname: Gherardi
authors.affiliation: Dipartimento di Matematica, Università di Pavia, Pavia, Italy.
authors.forename: Federico
authors.initials: F
authors.lastname: Bassetti
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, UMR 7238, Computational and Quantitative Biology, 15 rue de l'École de Médecine Paris, France.|CNRS, UMR 7238, Paris, France.
authors.forename: Marco
authors.initials: M
authors.lastname: Cosentino Lagomarsino