Fabrizi, S., Lippert, S., Pan, A., Ryan, M., 2024. Unanimity under Ambiguity.
Ellis (2016) introduced a variant of the classic (jury) voting game in which voters have ambiguous prior beliefs. He focussed on voting under majority rule and the implications of ambiguity for Condorcet’s Theorem. Ryan (2021) studied Ellis’ game when voting takes place under the unanimity rule. His focus was on the implications of ambiguity for the “jury paradox” (Feddersen and Pesendorfer, 1998). Neither paper described all equilibria of these games, though both authors identified equilibria with a very different structure to those in the respective games without ambiguity. We complete the description of all equilibria of voting games under the unanimity rule. In particular, we identify equilibria having the same form as those in Feddersen and Pesendorfer (1998), as well as equilibria with a “dual” form.
Lippert, S., Russell, H., Tremewan, J., 2024. Group size and Pledge-and-Review bargaining.
We conduct a laboratory experiment to test whether the efficacy of the pledge-and-review institution in the bilateral case reported in Lippert and Tremewan (2021) is robust to increased group size. This is a priori unclear, as with more than two players punishment for a low contribution by voting down a deal cannot be perfectly targeted, increasing the incentive to free ride. We find that the pledge-and-review institution remains effective in sustaining contributions and increasing efficiency. While the absolute efficiency gain of the pledge-and-review institution over a voluntary contribution mechanism increased, when controlling for group size there is a relative decline in the efficiency gain of the institution.
Fabrizi, S., Lippert, S., 2020. On moral hazard and joint R&D.
We analyze two entrepreneurs' choices of how much to invest in rival product innovation projects, and whether to conduct them competitively, in a cross-licensing agreement, or in an R&D joint venture. We distinguish late and early-stage projects and allow for cooperative and non-cooperative conduct in the product market ensuing an R&D joint venture. We find that early-stage projects are more likely carried out as stand-alone R&D or in cross-licensing agreements than late-stage projects; and that lenient enforcement of non-cooperative product-market conduct after R&D joint ventures should depend on the stage of the R&D project. We propose a `synergy - market-size defense.'
Fabrizi, S., Lippert, S., Rodrigues Neto, J.A., 2024. Attack, defense and the market for protection.
We study the market for the provision of protection. Its demand side arises from an interaction between heterogeneous populations of attackers and potentially connected defenders. Attackers decide whether to perpetrate untargeted attacks. Defenders decide whether to buy protection at a market price. If interconnected, unprotected defenders are also exposed to secondary attacks spreading through their network. With varying modes of attack, active attackers affect the cost of providing protection thereby inducing possible \textit{economies of use}. After providing sufficient conditions for the existence and uniqueness of a Nash equilibrium in the interaction between attackers and defenders, we analyze pricing incentives and protection coverage under alternative market structures. We discuss efficiency issues in the market for protection. Market concentration may be socially beneficial due to the internalization of economies of use. Higher connectedness may be socially beneficial due to increased incentives to buy protection.