@article{1139, abstract = {{We investigate the degree of price competition among telecommunication firms. Underlying a Bertrand model of price competition, we empirically model pricing behaviour in an oligopoly. We analyse panel data of individual pricing information of mobile phone contracts offered between 2011 and 2017. We provide empirical evidence that price differences as well as reputational effects serve as a signal to buyers and significantly affect market demand. Additionally, we find that brands lead to an increase in demand and thus are able to generate spillover effects even after price increase.}}, author = {{Kaimann, Daniel and Hoyer, Britta}}, journal = {{Applied Economics Letters}}, number = {{1}}, pages = {{54--57}}, publisher = {{Taylor and Francis Online}}, title = {{{Price competition and the Bertrand model: The paradox of the German mobile discount market}}}, doi = {{10.1080/13504851.2018.1436141}}, volume = {{26}}, year = {{2019}}, } @article{2256, abstract = {{Social psychology studies the "common enemy effect", the phenomenon that members of a group work together when they face an opponent, although they otherwise have little in common. An interesting scenario is the formation of an information network where group members individually sponsor costly links. Suppose that ceteris paribus, an outsider appears who aims to disrupt the information flow within the network by deleting some of the links. The question is how the group responds to this common enemy. We address this question for the homogeneous connections model of strategic network formation, with two-way flow of information and without information decay. For sufficiently low linkage costs, the external threat can lead to a more connected network, a positive common enemy effect. For very high but not prohibitively high linkage costs, the equilibrium network can be minimally connected and efficient in the absence of the external threat whereas it is always empty and ineffi cient in the presence of the external threat, a negative common enemy effect. For intermediate linkage costs, both connected networks and the empty network are Nash for certain cost ranges.}}, author = {{Hoyer, Britta and Haller, Hans}}, journal = {{Journal of Economic Behavior & Organization}}, pages = {{146--163}}, title = {{{The Common Enemy Effect under Strategic Network Formation and Disruption}}}, doi = {{10.1016/j.jebo.2019.03.011}}, volume = {{162}}, year = {{2019}}, } @article{80, abstract = {{Models on network formation have often been extended to include the potential of network disruption in recent years. Whereas the theoretical research on network formation under the threat of disruption has thus gained prominence, hardly any experimental research exists so far. In this paper, we therefore experimentally study the emergence of networks including the aspect of a known external threat by relating theoretical predictions by Dzuibiński and Goyal (2013) to actual observed behaviour. We deal with the question if subjects in the role of a strategic Designer are able to form safe networks for least costs while facing a strategic Adversary who is going to attack their networks. Varying the costs for protecting nodes, we designed and tested two treatments with different predictions for the equilibrium network and investigated whether one of the least cost equilibrium networks was more likely to be reached. Furthermore, the influence of the subjects’ farsightedness on their decision-making process was elicited and analysed. We find that while subjects are able to build safe networks in both treatments, equilibrium networks are only built in one of the two treatments. In the other treatment, predominantly safe networks are built but they are not for least costs. Additionally, we find that farsightedness –as measured in our experiment– has no influence on whether subjects are able to build safe or least cost equilibrium networks. Two robustness settings with a reduced external threat or more liberties to modify the initial networks qualitatively confirm our results. Overall, in this experiment observed behaviour is only partially in line with the theoretical predictions by Dzuibiński and Goyal (2013).}}, author = {{Endres, Angelika Elfriede and Recker, Sonja and Mir Djawadi, Behnud and Hoyer, Britta}}, journal = {{Journal of Economic Behavior and Organization }}, pages = {{708--734}}, title = {{{Network Formation and Disruption - An Experiment: Are equilibrium networks too complex?}}}, doi = {{10.1016/j.jebo.2018.11.004}}, volume = {{157}}, year = {{2019}}, } @phdthesis{8080, abstract = {{This thesis investigates approximate pure Nash equilibria in different game-theoretic models. In such an outcome, no player can improve her objective by more than a given factor through a deviation to another strategy. In the first part, we investigate two variants of Congestion Games in which the existence of pure Nash equilibria is guaranteed through a potential function argument. However, the computation of such equilibria might be hard. We construct and analyze approximation algorithms that enable the computation of states with low approximation factors in polynomial time. To show their guarantees we use sub games among players, bound the potential function values of arbitrary states and exploit a connection between Shapley and proportional cost shares. Furthermore, we apply and analyze sampling techniques for the computation of approximate Shapley values in different settings. In the second part, we concentrate on the existence of approximate pure Nash equilibria in games in which no pure Nash equilibria exist in general. In the model of Coevolving Opinion Formation Games, we bound the approximation guarantees for natural states nearly independent of the specific definition of the players' neighborhoods by applying a concept of virtual costs. For the special case of only one influential neighbor, we even show lower approximation factors for a natural strategy. Then, we investigate a two-sided Facility Location Game among facilities and clients on a line with an objective function consisting of distance and load. We show tight bounds on the approximation factor for settings with three facilities and infinitely many clients. For the general scenario with an arbitrary number of facilities, we bound the approximation factor for two promising candidates, namely facilities that are uniformly distributed and which are paired.}}, author = {{Feldotto, Matthias}}, title = {{{Approximate Pure Nash Equilibria in Congestion, Opinion Formation and Facility Location Games}}}, doi = {{10.17619/UNIPB/1-588}}, year = {{2019}}, } @article{7413, author = {{Gutt, Dominik and Neumann, Jürgen and Zimmermann, Steffen and Kundisch, Dennis and Chen, J.}}, journal = {{Journal of Strategic Information Systems}}, number = {{2}}, pages = {{104--117}}, title = {{{Design of Review Systems – A Strategic Instrument to shape Online Reviewing Behavior and Economic Outcomes}}}, volume = {{28}}, year = {{2019}}, } @techreport{7630, abstract = {{In this paper, we analyze a credence goods model adjusted to the health care market with regulated prices and heterogeneous experts. Experts are physicians and are assumed to differ in their cost of treating a small problem. We investigate the effects of this heterogeneity on the physicians’ level of fraud and on the patients’ search for second opinions. We find that introducing a fraction of more efficient low-cost physicians always increases social welfare, but in some cases only because of the raised physicians’ surplus. When the low-cost physicians’ cost advantage is small, imposing a share of low-cost physicians does not change the equilibrium fraud level. When the cost advantage is large, however, different changes in the fraud level occur depending on the share of generated low-cost physicians, the search rate and the initial level of fraud.}}, author = {{Heinzel, Joachim Maria Josef}}, keywords = {{credence goods, treatment efficiency, heterogeneous experts, overcharging}}, publisher = {{CIE Working Paper Series}}, title = {{{Credence Goods Markets with Heterogeneous Experts}}}, volume = {{118}}, year = {{2019}}, } @inproceedings{7636, abstract = {{Self-stabilizing overlay networks have the advantage of being able to recover from illegal states and faults. However, the majority of these networks cannot give any guarantees on their functionality while the recovery process is going on. We are especially interested in searchability, i.e., the functionality that search messages for a specific node are answered successfully if a node exists in the network. In this paper we investigate overlay networks that ensure the maintenance of monotonic searchability while the self-stabilization is going on. More precisely, once a search message from node u to another node v is successfully delivered, all future search messages from u to v succeed as well. We extend the existing research by focusing on skip graphs and present a solution for two scenarios: (i) the goal topology is a super graph of the perfect skip graph and (ii) the goal topology is exactly the perfect skip graph. }}, author = {{Luo, Linghui and Scheideler, Christian and Strothmann, Thim Frederik}}, booktitle = {{Proceedings of the 2019 IEEE 33rd International Parallel and Distributed Processing Symposium (IPDPS '19)}}, location = {{Rio de Janeiro, Brazil}}, title = {{{MultiSkipGraph: A Self-stabilizing Overlay Network that Maintains Monotonic Searchability}}}, year = {{2019}}, } @misc{8351, author = {{Nutt, Florian}}, title = {{{Vertrauensbildung und Reputationssysteme auf digitalen B2B-Märkten - Ein klassifizierender Überblick}}}, year = {{2019}}, } @misc{8530, author = {{Beckhoff, Yvonne Maria}}, title = {{{There's an App for that - Ein Literaturüberblick über Erfolgsfaktoren für App-Downloads}}}, year = {{2019}}, } @inproceedings{8534, abstract = {{We propose two protocols for distributed priority queues (denoted by 'heap' for simplicity in this paper) called SKEAP and SEAP. SKEAP realizes a distributed heap for a constant amount of priorities and SEAP one for an arbitrary amount. Both protocols build on an overlay, which induces an aggregation tree on which heap operations are aggregated in batches, ensuring that our protocols scale even for a high rate of incoming requests. As part of SEAP we provide a novel distributed protocol for the k-selection problem that runs in time O(log n) w.h.p. SKEAP guarantees sequential consistency for its heap operations, while SEAP guarantees serializability. SKEAP and SEAP provide logarithmic runtimes w.h.p. on all their operations. SKEAP and SEAP provide logarithmic runtimes w.h.p. on all their operations with SEAP having to use only O(log n) bit messages.}}, author = {{Feldmann, Michael and Scheideler, Christian}}, booktitle = {{Proceedings of the 31st ACM Symposium on Parallelism in Algorithms and Architectures (SPAA)}}, pages = {{287----296}}, publisher = {{ACM}}, title = {{{Skeap & Seap: Scalable Distributed Priority Queues for Constant and Arbitrary Priorities}}}, doi = {{10.1145/3323165.3323193}}, year = {{2019}}, } @misc{8799, author = {{Groh, Andreas}}, title = {{{Ideenbewertung durch die Crowd - Ein klassifizierender Literaturüberblick}}}, year = {{2019}}, } @misc{8840, author = {{Fath, Jerome Louis}}, title = {{{# Fail - Ein Literaturüberblick über Online-Bewertungen zu Produkt- und Dienstleistungsfehlern}}}, year = {{2019}}, } @inproceedings{8871, author = {{Augustine, John and Ghaffari, Mohsen and Gmyr, Robert and Hinnenthal, Kristian and Kuhn, Fabian and Li, Jason and Scheideler, Christian}}, booktitle = {{Proceedings of the 31st ACM Symposium on Parallelism in Algorithms and Architectures}}, pages = {{69----79}}, publisher = {{ACM}}, title = {{{Distributed Computation in Node-Capacitated Networks}}}, doi = {{10.1145/3323165.3323195}}, year = {{2019}}, } @techreport{8873, abstract = {{We analyze a credence goods market adapted to a health care market with regulated prices, where physicians are heterogeneous regarding their fairness concerns. The opportunistic physicians only consider monetary incentives while the fair physicians, in addition to a monetary payoff, gain an non-monetary utility from being honest towards patients. We investigate how this heterogeneity affects the physicians’ equilibrium level of overcharging and the patients’ search for second opinions (which determines overall welfare). The impact of the heterogeneity on the fraud level is ambiguous and depends on several factors such as the size of the fairness utility, the share of fair physicians, the search level and the initial fraud level. Introducing heterogeneity does not affect the fraud or the search level when the share of fair physicians is small. However, when social welfare is not at its maximum, social welfare always increases if we introduce a sufficiently large share of fair physicians.}}, author = {{Heinzel, Joachim Maria Josef}}, keywords = {{credence goods, heterogeneous experts, fairness, overcharging}}, publisher = {{CIE Working Paper Series}}, title = {{{Credence Goods Markets with Fair and Opportunistic Experts}}}, volume = {{119}}, year = {{2019}}, } @inproceedings{9774, author = {{Neumann, Jürgen and Gutt, Dominik}}, booktitle = {{Proceedings of the 25th Americas Conference on Information Systems (AMCIS)}}, location = {{Cancun, Mexico}}, title = {{{Money Makes the Reviewer Go Round – Ambivalent Effects of Online Review Elicitation in B2B Markets}}}, year = {{2019}}, } @inproceedings{9775, author = {{Neumann, Jürgen and Gutt, Dominik and Görzen, Thomas and Kundisch, Dennis}}, booktitle = {{Proceedings of the 25th Americas Conference on Information Systems (AMCIS)}}, location = {{Cancun, Mexico}}, title = {{{When does Local Status Matter? – The Relationship between Reviewer Location and Perceived Usefulness of Online Reviews}}}, year = {{2019}}, } @inproceedings{9776, author = {{Poniatowski, Martin and Neumann, Jürgen and Kundisch, Dennis}}, booktitle = {{Proceedings of the 25th Americas Conference on Information Systems (AMCIS)}}, location = {{Cancun, Mexico}}, title = {{{Reviewing the Vendor or the Product – Analyzing Vendor versus Product Representation in B2B Review Systems}}}, year = {{2019}}, } @inproceedings{9777, author = {{Poniatowski, Martin and Neumann, Jürgen and Görzen, Thomas and Kundisch, Dennis}}, booktitle = {{Proceedings of the 27th European Conference on Information Systems (ECIS)}}, location = {{Stockholm, Sweden}}, title = {{{Organizing Their Thoughts – How Online Review Templates Affect the Review Text}}}, year = {{2019}}, } @inproceedings{9778, author = {{Gutt, Dominik and Neumann, Jürgen}}, booktitle = {{Proceedings of the 27th European Conference on Information Systems (ECIS)}}, location = {{Stockholm, Sweden}}, title = {{{The Virtues of Anonymity - An Empirical Investigation of the Relationship between B2B Online Ratings and Reviewer Self-Disclosure}}}, year = {{2019}}, } @inproceedings{9779, author = {{Neumann, Jürgen and Gutt, Dominik}}, booktitle = {{Proceedings of the 27th European Conference on Information Systems (ECIS)}}, location = {{Stockholm, Sweden}}, title = {{{He Who Pays the Piper Calls the Tune: Online Review Elicitation by Sellers and Third-Party Platforms in B2B Markets}}}, year = {{2019}}, }