Dr. Stefan Sorg

Former Research Fellow

Innovation and Entrepreneurship Research



Areas of Interest:

Economics of Innovation, Economics of Litigation

Academic Résumé

2014 - 2018
Junior Research Fellow at Max Planck Institute for Innovation and Competition (Innovation and Entrepreneurship Research). Doctoral Thesis: “Essays on the Economics of Patents: Post-Grant Review, Subsequent Innovation, and Selection for Litigation.”

2013 - 2014
Master's Thesis: „Interaction Quantum Quenches in the One-Dimensional Bose-Hubbard Model“, Supervisor: PD Dr. Fabian Heidrich-Meisner, Chair for Theoretical Nanophysics (Prof. Dr. Ulrich Schollwöck), LMU Munich

2011 - 2014
Studies in Physics (Graduate, M.Sc.) at LMU Munich (semester abroad at the INP Grenoble / UJF Grenoble)

2011
Bachelor's Thesis: “Optimization of a Beam Pointing System for Quantum Cryptography“, Group “Experimental Quantum Physics“, Prof. Dr. Harald Weinfurter, Chair Prof. Dr. Theodor Hänsch, LMU Munich

2008 - 2011
Studies in Physics (Undergraduate, B.Sc.) at LMU Munich (semester abroad at the University of California, Berkeley)

Scholarships

2013 - 2014
Germany Scholarship (Deutschlandstipendium), LMU Munich

2012 - 2013
ERASMUS Scholarship for Staying at the INP Grenoble

2010
DAAD Scholarship USA for Staying at the University of California, Berkeley

Publications

Articles in Refereed Journals

Nagler, Markus; Sorg, Stefan (2020). The Disciplinary Effect of Post-Grant Review – Causal Evidence from European Patent Opposition, Research Policy, 49 (3), 103915. DOI

  • We study the causal impact of invalidating marginally valid patents during post-grant opposition at the European Patent Office on affected inventors’ subsequent patenting. We exploit exogenous variation in invalidation by leveraging the participation of a patent’s original examiner in the opposition division as an instrument. We find a disciplinary effect of invalidation: Affected inventors file significantly fewer patent applications in the decade after the decision. The effect is entirely driven by a reduction in low-quality filings, i.e., filings that examiners associate with prior art that threatens the application’s novelty or inventive step. We do not observe shifts into national patenting.

Gaessler, Fabian; Harhoff, Dietmar; Sorg, Stefan (2017). Patents and Cumulative Innovation – Evidence from Post-Grant Patent Oppositions, Academy of Management Proceedings, 2017,1, 12800. DOI

  • Using large-scale data on opposition to patents at the European Patent Office (EPO), we investigate the causal effect of a patent’s invalidation on follow-on inventions. We introduce a new instrumental variable exploiting the participation or absence of the patent examiner in the opposition proceeding. According to our baseline model, patent invalidation leads to a highly significant and sizable increase of forward citations. While this is in line with previous studies, disentangling the effect leads us to results that stand in stark contrast to some of the literature. We find that the effects are most pronounced for patents in discrete technology areas, for areas where patent thickets are absent and for patents which are not protected by ""patent fences"". Moreover, the effect is particularly strong for relatively small patent holders facing comparatively small follow-on innovators.

Sorg, Stefan; Vidmar, L.; Pollet, L.; Heidrich-Meisner, F. (2014). Relaxation and thermalization in the one-dimensional Bose-Hubbard model: A case study for the interaction quantum quench from the atomic limit, Physical Review A, 2014 (90). DOI

  • Motivated by recent experiments, we study the relaxation dynamics and thermalization in the one-dimensional Bose-Hubbard model induced by a global interaction quench. Specifically, we start from an initial state that has exactly one boson per site and is the ground state of a system with infinitely strong repulsive interactions at unit filling. Using exact diagonalization and the density-matrix renormalization-group method, we compute the time dependence of such observables as the multiple occupancy and the momentum distribution function. Typically, the relaxation to stationary values occurs over just a few tunneling times. The stationary values are identical to the so-called diagonal ensemble on the system sizes accessible to our numerical methods and we further observe that the microcanonical ensemble describes the time averages of many observables reasonably well for small and intermediate interaction strength. The expectation values of observables in the canonical ensemble agree quantitatively with the time averages obtained from the quench at small interaction strengths, and qualitatively provide a good description even in parameter regimes where the microcanonical ensemble is not applicable due to finite-size effects. We discuss our numerical results in the framework of the eigenstate thermalization hypothesis. Moreover, we also observe that the diagonal and the canonical ensembles are practically identical for our initial conditions already on the level of their respective energy distributions for small interaction strengths. Finally, we discuss implications of our results for the interpretation of a recent sudden expansion experiment [Phys. Rev. Lett. 110, 205301 (2013)], in which the same interaction quench was realized.

Discussion Papers

Gaessler, Fabian; Harhoff, Dietmar; Sorg, Stefan (2019). Bargaining Failure and Freedom to Operate: Re-Evaluating the Effect of Patents on Cumulative Innovation, Max Planck Institute for Innovation & Competition Research Paper, No. 19-11. DOI

Gaessler, Fabian; Harhoff, Dietmar; Sorg, Stefan (2019). Bargaining Failure and Freedom to Operate: Re-evaluating the Effect of Patents on Cumulative Innovation, CEPR Discussion Paper, 13969.

  • We investigate the causal effect of patent rights on cumulative innovation, using large-scale data that approximate the patent universe in its technological and economic variety. We introduce a novel instrumental variable for patent invalidation that exploits personnel scarcity in post-grant opposition at the European Patent Ofï¬ ce. We ï¬ nd that patent invalidation leads to a highly signiï¬ cant and sizeable increase of follow-on inventions. The effect is driven by cases where the removal of the individual exclusion right creates substantial freedom to operate for third parties. Importantly, our results suggest that bargaining failure between original and follow-on innovators is not limited to environments commonly associated with high transaction costs.
  • https://ideas.repec.org/p/cpr/ceprdp/13969.html
  • Also published as: Max Planck Institute for Innovation & Competition Research Paper No. 19-11

Presentations and Lectures

30.08.2018
Marginal Patents and the Supply of Ideas
Doctoral Seminar, Max Planck Institute for Innovation and Competition
Location: Kreuth


31.05.2018
Patent Invalidation, Inventor Productivity, and the Direction of Innovation
Spring Meeting of Young Economists 2018, Universitat de les Illes Balears
Location: Seville, Spain


14.03.2018
Patent Invalidation, Inventor Productivity, and the Direction of Innovation
Doctoral Seminar, Max Planck Institute for Innovation and Competition
Location: Zugspitze

Projects