Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Stefan Wagner is active.

Publication


Featured researches published by Stefan Wagner.


Management Science | 2009

The Duration of Patent Examination at the European Patent Office

Dietmar Harhoff; Stefan Wagner

We analyze the duration and outcomes of patent examination at the European Patent Office utilizing an unusually rich data set covering a random sample of 215,265 applications filed between 1982 and 1998. In our empirical analysis, we distinguish between three groups of determinants: applicant characteristics, indicators of patent quality and value, and determinants that affect the complexity of the examination task. The results from an accelerated failure time model indicate that more controversial claims lead to slower grants but faster withdrawals, whereas well-documented applications are approved faster and withdrawn more slowly. We find strong evidence that applicants accelerate grant proceedings for their most valuable patents, but that they also prolong the battle for such patents if a withdrawal or refusal is imminent. This paper develops implications of these results for managerial decision making in research and development and innovation management.


Journal of Industrial Economics | 2013

Incidence and Growth of Patent Thickets - The Impact of Technological Opportunities and Complexity

Georg von Graevenitz; Stefan Wagner; Dietmar Harhoff

We investigate incidence and evolution of patent thickets. Our empirical analysis is based on a theoretical model of patenting in complex and discrete technologies. The model captures how competition for patent portfolios and complementarity of patents affect patenting incentives. We show that lower technological opportunities increase patenting incentives in complex technologies while they decrease incentives in discrete technologies. Also, more competitors increase patenting incentives in complex technologies and reduce them in discrete technologies. To test these predictions a new measure of the density of patent thickets is introduced. European patent citations are used to construct measures of fragmentation and technological opportunity. Our empirical analysis is based on a panel capturing patenting behavior of 2074 firms in 30 technology areas over 15 years. GMM estimation results confirm the predictions of our theoretical model. The results show that patent thickets exist in 9 out of 30 technology areas. We find that decreased technological opportunities are a surprisingly strong driver of patent thicket growth.


Diabetes | 1993

Diabetic Neuropathy 3 Years After Successful Pancreas and Kidney Transplantation

Wolfgang Müller-Felber; R. Landgraf; Ralf Scheuer; Stefan Wagner; C. D. Reimers; J. Nusser; Deitmar Abendroth; Wolf-Dieter Illner; Walter Land

Twenty-seven patients with successful transplantation and a control group of 14 patients with early rejection of the pancreas graft but functioning kidney graft were examined in a prospective study for 3 yr. Before transplantation, all patients had long-standing type I diabetes with advanced secondary complications, including end-stage diabetic nephropathy. After transplantation in the patients of both groups, kidney function was almost normal. Mean HbA1 levels were normal in the group with pancreas graft survival. In the control group, HbA1 levels were, on average, 1.5% higher compared with the group with pancreas survival (P = 0.00005). After 3 yr, the patients with functioning pancreas graft showed fewer symptoms (mean difference 1.0 in a symptom score ranging from 0 to 16, P = 0.004) compared with the control group. No statistically significant difference between both groups concerning clinical signs of polyneuropathy could be observed. In the pancreas and kidney transplantation group, peroneal and median nerve conduction velocities increased 7.2 m/s (P < 0.01) and 3.5 m/s (P < 0.05), respectively, whereas no increase was registered in the control group. The change of median and sural sensory nerve conduction velocities, peroneal and median compound muscle action potentials, and sural and median sensory action potentials was insignificant. In conclusion, although the improvement of clinical symptoms and neurophysiological signs of polyneuropathy was modest in the pancreas and kidney transplantation group, our data suggest that successful pancreas transplantation is able not only to halt the progression of diabetic polyneuropathy but also to improve it to some extent even at a far advanced stage.


Statistical Modelling | 2007

Zero-inflated generalized Poisson models with regression effects on the mean, dispersion and zero-inflation level applied to patent outsourcing rates

Claudia Czado; Vinzenz Erhardt; Aleksey Min; Stefan Wagner

This paper focuses on an extension of zero-inflated generalized Poisson (ZIGP) regression models for count data. We discuss generalized Poisson (GP) models where dispersion is modelled by an additional model parameter. Moreover, zero-inflated models, in which overdispersion is assumed to be caused by an excessive number of zeros, are discussed. In addition to ZIGP models considered by several authors, we now allow for regression on the overdispersion and zero-inflation parameters. Consequently, we propose tools for an exploratory data analysis on the dispersion and zero-inflation level. An application dealing with outsourcing of patent filing processes will be used to compare these nonnested models. The model parameters are fitted by maximum likelihood using our R package ‘ZIGP’ available on the Comprehensive RArchive Network (CRAN). Asymptotic normality of the Maximum Likelihood (ML) estimates in this non-exponential setting is proven. Standard errors are estimated using the asymptotic normality of the estimates. Appropriate exploratory data analysis tools are developed. Also, a model comparison using Akaike Information Criterion (AIC) statistics and Vuong tests is carried out. For the given data, our extended ZIGP regression model will prove to be superior over GP and zero-inflated Poisson (ZIP) models, and even over ZIGP models, with constant overall dispersion and zero-inflation parameters demonstrating the usefulness of our proposed extensions.


International Journal of Innovation Management | 2008

OUTLAW COMMUNITY INNOVATIONS

Celine Schulz; Stefan Wagner

Recent studies of outlaw communities provide qualitative evidence of their existence and the organisation of the underlying innovation processes. We provide descriptive results from a large scale survey of two online outlaw communities focussing on Microsofts XBox (a gaming console). Based on the previous findings, we identify two types of participants in outlaw communities — user innovators and adopters. Based on 2256 responses, we find that users modify their XBox mainly to be able to increase the set of available functions of their XBox. Users are also motivated to modify their XBox for the sake of having fun and to conduct pirate behaviour. Finally, results from our survey also suggest that user innovators are largely intrinsically motivated by fun and the intellectual stimulation of writing code for homebrew software.


Virchows Archiv | 1993

Fibre type specific expression of Leu19-antigen and N-CAM in skeletal muscle in various stages after experimental denervation

Wolfgang Müller-Felber; Klaus Kullmer; Petra Fischer; Carl-Detlev Reimers; Stefan Wagner; Ullrich Harland; Martin Schmidt-Achert; D. Pongratz

Leu-19 antigen, which seems to be identical with neural cell adhesion molecule (N-CAM), plays a major role in the innervation of muscle cells, and in adult muscle appears after denervation and during regeneration of muscle fibres, where it acts as part of a signalling system increasing the probability of re-innervation. This combined enzyme-histochemical and immunohistochemical study examined whether this signalling process was regulated in a uniform or differential pattern for type 1 and type 2 muscle fibres. The subscapular nerve of 18 rabbits was transsected with subsequent complete denervation of the supraspinatus muscle. Leu19 and N-CAM immunohistochemistry was performed 2 to 64 days after surgery. Whereas in normal muscle there are virtually no Leu-19/N-CAM positive muscle fibres; from day 2 after denervation an increasing proportion of fibres expressed Leu-19/N-CAM, prior to any neurogenic atrophy. In the early stage of denervation Leul9/N-CAM expression was confined to type 1 fibres. After 11 days nearly all fibres were Leul9/N-CAM positive irrespective of their fibre type. Sixty-four days after denervation type 1 fibres became Leu19/N-CAM negative, while atrophic type 2 fibres showed intensive staining. Thus, expression of Leu-19 antigenity is differently regulated in both fibre types.


Management Science | 2016

Conflict Resolution, Public Goods, and Patent Thickets

Dietmar Harhoff; Georg von Graevenitz; Stefan Wagner

Postgrant validity challenges at patent offices rely on the private initiative of third parties to correct mistakes made by patent offices. We hypothesize that incentives to bring postgrant validity challenges are reduced when many firms benefit from revocation of a patent and when firms are caught up in patent thickets. Using data on opposition to patents at the European Patent Office we show that opposition decreases in fields in which many others profit from patent revocations. Moreover, in fields with a large number of mutually blocking patents, the incidence of opposition is sharply reduced, particularly among large firms and firms that are caught up directly in patent thickets. These findings indicate that postgrant patent review may not constitute an effective correction device for erroneous patent grants in technologies affected by either patent thickets or highly dispersed patent ownership. This paper was accepted by Lee Fleming, entrepreneurship and innovation .


Archive | 2008

Managerial Succession and Organizational Performance

Stefan Wagner

It has been widely studied how organizational performance changes after the replacement of the responsible manager. However, there is little evidence how changes in the business environment interact with the efficiency on management replacements. In this paper, I explicitly consider the effect of a change in the environment of organizations on post-replacement effects with regard to organizational performance. Analyzing the performance effect of coach replacements in the German Soccer League prior and after the introduction of the 3-points-rule I find that the magnitude of the performance effect of coach replacements depends on the reward scheme applied in soccer matches. The empirical analysis of the paper confirms predictions from the theoretical model: coach replacements have more favorable effects on team performance under the 3-points-rule than under the 2-points-rule.


World Scientific Book Chapters | 2008

Outlaw Community Innovations

Celine Schulz; Stefan Wagner

Recent studies of outlaw communities provide qualitative evidence of their existence and the organisation of the underlying innovation processes. We provide descriptive results from a large scale survey of two online outlaw communities focussing on Microsofts XBox. In line with previous findings, we identify two types of participants in outlaw communities - user innovators and adopters. Based on 2,256 responses, we find that users modify their XBox mainly to be able to increase the set of available functions of their XBox. Users are also motivated to modify their XBox for the sake of having fun and to conduct pirate behaviour. Finally, the results from our survey suggest that user innovators are largely intrinsically motivated by fun and the intellectual stimulation of writing code for homebrew software.


Archive | 2008

Make-or-Buy Decisions in Patent Related Services

Stefan Wagner

Among the most prominent theoretical frameworks dealing with the economic underlyings of firms’ make-or-buy decisions are Transaction Cost Economics (TCE) and the Resourced Based View (RBV). Relying on panel data covering 107 European firms over eight years I test predictions from both TCE and RBV with regard to the outsourcing of patent related services simultaneously. Modelling the share of outsourced patent applications in a Negative Binomial Panel Regression Model I find joint explanatory power of both approaches. My findings support previous literature arguing for an integration of TCE and RBV to a comprehensive theoretical framework of firms make-or-buy decisions.

Collaboration


Dive into the Stefan Wagner's collaboration.

Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar

C. D. Reimers

University of Göttingen

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar

Paola Giuri

Sant'Anna School of Advanced Studies

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Researchain Logo
Decentralizing Knowledge