Robustness to strategic uncertainty

We introduce a criterion for robustness to strategic uncertainty in games with continuum strategy sets. We model a player's uncertainty about another player's strategy as an atomless probability distribution over that player's strategy set. We call a strategy profile robust to strategic uncertainty if it is the limit, as uncertainty vanishes, of some sequence of strategy profiles in which every player's strategy is optimal under his or her uncertainty about the others. When payoff functions are continuous we show that our criterion is a refinement of Nash equilibrium and we also give sufficient conditions for existence of a robust strategy profile. In addition, we apply the criterion to Bertrand games with convex costs, a class of games with discontinuous payoff functions and a continuum of Nash equilibria. We show that it then selects a unique Nash equilibrium, in agreement with some recent experimental findings.     

The Tunisia Wheat Market in the Context of World Price Volatility: A Stochastic Partial Equilibrium Approach

Food security is a key objective of agricultural and food policy in Tunisia. The 2007–2008 food crisis highlighted the negative impacts of price volatility on international markets both in terms of food insecurity and budget exposure. Tunisian food subsidy expenditures ranged from $180 million to $710 million in 2006–2010, so volatile world prices meant volatile subsidy costs. Moreover, cereal production in Tunisia still has much instability due to climate conditions, which also influences imports and, consequently, subsidy expenditures. This study applies a structural model to conduct stochastic analyses of trade and policy impacts on food security and budget expenditures in the Tunisian wheat market. The methodology disaggregates durum wheat and soft wheat markets and generates projections of import prices of durum wheat and soft wheat, using projections of world prices provided by the Food and Agricultural Policy Research Institute at University of Missouri (FAPRI-MU). The key innovation is the generated stochastic analyses of subsidy costs based on stochastic world price projections and stochastic domestic wheat yields based on historic yield variances. The analysis highlights the sensitivity of subsidy costs to world prices, volumes imported and domestic production, so that alternative policy tools can be considered.     

Life Expectancy Heterogeneity and the Political Support for Collective Annuities

Individuals, differing in productivity and life expectancy, vote over the size and type of a collective annuity. Its type is represented by the fraction of the contributive (Bismarckian) component (based on the worker's past earnings) as opposed to the non‐contributive (Beveridgean) part (based on average contribution). The equilibrium collective annuity is either a large mostly Bismarckian program, a smaller pure Beveridgean one (in accordance with empirical evidence), or nil. A larger correlation between longevity and productivity, or a larger average life expectancy, both make the equilibrium collective annuity program more Beveridgean, although at the expense of its size.     

Analysing job creation effects of scaling up infrastructure spending in South Africa

In a first for South Africa, this article draws on literature on infrastructure productivity to model dynamic economy-wide employment impacts of infrastructure investment funded with different fiscal tools. Using a dynamic computable general equilibrium model, the South African investment plan is modelled, given the infrastructure externality. Alternative fiscal scenarios to finance the policy are modelled in the article. In the long run, unemployment decreases for all types of workers under one of the scenarios. In the short run, only elementary occupation workers benefit from a decrease in unemployment; for the rest, unemployment rises.     

Economic and Household Impacts of Projected Policy Changes for the Irish Agri‐food Sector

The policy environment for the Irish agri‐food sector could change rapidly in the coming decade. A potentially positive factor will be the elimination of milk quotas in 2015, although a potentially negative factor will be further trade liberalisation and increased import competition. These changes come on top of the move to decouple direct aids to farmers in 2005 as part of the Mid‐Term Review of the EU's Common Agricultural Policy agreed in 2003. This paper examines these reforms and their impacts on the Irish economy and income distribution using a CGE model particularly rich in detail on the agri‐food sectors, differentiated household groups, and agricultural policy instruments including their links to productive factors and households. The results suggest that the past and projected changes in the policy environment have, in sum, a small positive impact on GDP and household income. However, the gains and losses are unequally distributed across sectors and household groups due to the highly differentiated distribution of support and protection. Although all households generally gain from the sequence of policy reforms in the long run, some experience strong adverse effects from particular reforms and in the medium term.     

Econometrics and equilibrium models

In Rational Econometric Man, Edward Nell and Karim Errouaki present a welcome and timely case for the view that econometrics and econometric model-building may not be the magic tools to solve all empirical questions despite what many seem to have thought they were in the 1960s. Here I examine some possible problems with econometric models that have to do with their usually taking the form of equilibrium models. Some of these problems were recognized by Trygve Haavelmo decades ago. And as Aris Spanos has recently discussed, the problems are often the result of what we say in our textbooks. Some problems have to do with what we mean by econometric parameters and others with how we use probabilities.     

Robust grain supply chain design considering post-harvest loss and harvest timing equilibrium

This paper presents a bi-level robust optimization model, where a food company maximizes its profit and minimizes post-harvest loss by optimally deploying grain processing/storage facilities and determining grain purchase price, while a group of spatially distributed non-cooperative farmers determine harvest time, shipment, storage, and market decisions under yield uncertainty and market equilibrium. The non-cooperative behavior of the food company and the farmers is represented by a bi-level Stackelberg leader follower’s game model with mixed-integer decision variables. The proposed model and solution approach are applied to case studies for Illinois and Brazil.     

GAMBLING IN CONTESTS WITH REGRET

This paper discusses the gambling contest introduced in Seel and Strack (2013, Gambling in Contests, Journal of Economic Theory, 148(5), 2033–2048) and considers the impact of adding a penalty associated with failure to follow a winning strategy. The Seel and Strack model consists of n‐agents each of whom privately observes a transient diffusion process and chooses when to stop it. The player with the highest stopped value wins the contest, and each player's objective is to maximize her probability of winning the contest. We give a new derivation of the results of Seel and Strack based on a Lagrangian approach. Moreover, we consider an extension of the problem to a behavioral finance context in the sense of regret theory. In particular, an agent is penalized when her chosen strategy does not win the contest, but there existed an alternative strategy that would have resulted in victory.     

The veto mechanism in atomic differential information economies

We establish new characterizations of Walrasian expectations equilibria based on the veto mechanism in the framework of differential information economies with a complete finite measure space of agents. We show that it is enough to consider the veto power of a single coalition, consisting of the entire set of agents, to obtain the Aubin private core. Moreover, we investigate on the veto power of arbitrarily small and big coalitions, providing an extension to mixed markets of well known Schmeidler (1972) and Vind’s (1972) results in terms of Aubin private core allocations.     

Pairwise epistemic conditions for Nash equilibrium

We introduce a framework for modeling pairwise interactive beliefs and provide an epistemic foundation for Nash equilibrium in terms of pairwise epistemic conditions locally imposed on only some pairs of players. Our main result considerably weakens not only the standard sufficient conditions by Aumann and Brandenburger (1995), but also the subsequent generalization by Barelli (2009). Surprisingly, our conditions do not require nor imply mutual belief in rationality.