Mean–variance portfolio selection with ‘at-risk’ constraints and discrete distributions

We examine the impact of adding either a VaR or a CVaR constraint to the mean–variance model when security returns are assumed to have a discrete distribution with finitely many jump points. Three main results are obtained. First, portfolios on the VaR-constrained boundary exhibit (K + 2)-fund separation, where K is the number of states for which the portfolios suffer losses equal to the VaR bound. Second, portfolios on the CVaR-constrained boundary exhibit (K + 3)-fund separation, where K is the number of states for which the portfolios suffer losses equal to their VaRs. Third, an example illustrates that while the VaR of the CVaR-constrained optimal portfolio is close to that of the VaR-constrained optimal portfolio, the CVaR of the former is notably smaller than that of the latter. This result suggests that a CVaR constraint is more effective than a VaR constraint to curtail large losses in the mean–variance model.     

Exchange Rates,Employment and Labour Market Rigidity

In this paper, we study the effect of labour market rigidity on the impact of exchange rate shocks on employment. We use a panel dataset comprising 22 manufacturing sectors across 23 OECD countries. In our econometric model, the impact of exchange rate fluctuations on sectoral employment is mediated by the degree of openness and by a measure of labour market rigidity: the OECD's employment protection legislation (EPL) index. Our results suggest that greater labour market rigidity reduces the impact of exchange rate shocks on employment. This effect is statistically significant for low‐technology sectors.     

Robust portfolio estimation under skew-normal return processes

In this paper, we study issues related to the optimal portfolio estimators and the local asymptotic normality (LAN) of the return process under the assumption that the return process has an infinite moving average (MA) (∞) representation with skew-normal innovations. The paper consists of two parts. In the first part, we discuss the influence of the skewness parameter δ of the skew-normal distribution on the optimal portfolio estimators. Based on the asymptotic distribution of the portfolio estimator ? for a non-Gaussian dependent return process, we evaluate the influence of δ on the asymptotic variance V(δ) of ?. We also investigate the robustness of the estimators of a standard optimal portfolio via numerical computations. In the second part of the paper, we assume that the MA coefficients and the mean vector of the return process depend on a lower-dimensional set of parameters. Based on this assumption, we discuss the LAN property of the return's distribution when the innovations follow a skew-normal law. The influence of δ on the central sequence of LAN is evaluated both theoretically and numerically.     

A copula‐based approach to the simultaneous estimation of group and meta‐frontiers by constrained maximum likelihood

Existing approaches to the meta‐frontier estimation consist of two stages where the estimates of the local frontier parameters obtained in the first step are used to estimate meta‐frontier parameters by means of a linear or quadratic minimisation procedure in the second. Since it was shown by Schmidt (Review of Economics and Statistics 58: 238) that the second step is equivalent to constrained maximisation of a likelihood function, we extend this idea and offer a copula‐based approach to the estimation of the parameters of both meta‐ and group frontiers in a one‐step setting. In this way, we ensure a single data‐generating mechanism for the estimated parameters, expand the set of potential meta‐frontiers and account for the fact that shocks to the individual production units may be correlated with shocks to the local technological environment as a whole. We apply our estimation methodology to a data set on the world agriculture and find that the deviations from the group frontiers are positively correlated with deviations from the meta‐frontier, which is a conclusion that is impossible to reach without accounting for stochastic dependence between the two deviation types represented by a copula.     

The Luxembourg Common Agricultural Policy Reform and the European Food Industries: What's at Stake?

On June 26, 2003, the European Union (EU) adopted a new reform of its Common Agricultural Policy (CAP). Its boldest measure is the creation of a Single Farm Payment that will replace most of the present direct payments. We address quantitatively three issues raised by this new reform, using a computable general equilibrium model that allows us to measure the impacts on the food industries as well as their role in the transmission of impacts along the food chain. The first issue examined is whether this reform helps the EU15 to remove the controversial export subsidies. Our numerical results show that this reform effectively reduces the amount of export subsidies but without removing them. Our second concern lies with the production and trade distortion impacts of CAP direct payments. We investigate this issue in the case of full decoupling, as well as partial decoupling as chosen by EU15 Member States. We find that they have rather similar effects on production and trade. Finally, we explore the employment effects, and findings indicate that this reform leads to a significant decline of farm labor and, by contrast, to a very modest impact on the employment level by food processors. Generally, food industries are only marginally affected by this CAP reform. L'Union européenne (UE) a adopté une nouvelle réforme de sa Politique agricole commune (PAC) en juin 2003. La mesure la plus audacieuse a été la création d'un paiement unique par exploitation pour remplacer la plupart des aides directes actuelles. Dans le présent article, nous avons examiné trois questions soulevées par cette réforme à l'aide d'un modèle d'équilibre général calculable qui nous a permis de mesurer les répercussions sur les industries alimentaires de même que le rôle de ces industries dans la transmission des répercussions dans la chaîne alimentaire. La première question visait à déterminer si cette réforme permettait à l'UE‐15 d'éliminer les subventions à l'exportation controversées. Nos résultats numériques ont montré que la réforme diminuait effectivement ces subventions sans toutefois les éliminer. La deuxième question portait sur les répercussions des paiements uniques de la PAC sur la production et la distorsion des échanges. Nous avons examiné cette question en utilisant le découplage total et le découplage partiel retenu par les États membres de l'UE. Nous avons trouvé que les effets sur la production et les échanges étaient plutôt similaires entre les deux options de découplage. Enfin, nous avons évalué les répercussions sur l'emploi et nos résultats ont indiqué que cette réforme entraînait une baisse significative de la main‐d'?uvre agricole contrairement à de très faibles répercussions pour les entreprises de transformation des aliments. En général, les industries agroalimentaires ne sont que légèrement touchées par cette réforme.     

The Economic Impact of Marena’s Investments on Sustainable Agricultural Systems in Honduras

This study examines the economic impact of sustainable agricultural production systems in Central America. In particular, we investigate the impact of investments promoted by the MARENA Programme in Honduras on the total value of agricultural production (TVAP) of its beneficiaries. Propensity Score Matching techniques along with the Difference‐in‐Differences framework are used to mitigate biases stemming from differences in observed as well as unobserved (time‐invariant) characteristics between beneficiaries and a control group. The econometric estimates suggest that MARENA has had a positive and significant effect on the TVAP of beneficiaries. In addition, the analysis shows that, under alternative scenarios, MARENA yielded higher than expected internal rates of return. The results of this study shed light on the response of small‐scale hillside farmers to economic incentives and lend support to the role of natural resource management projects in Central America as a tool to increase household income while also promoting the conservation of natural resources.     

Employment and Exchange Rates: The Role of Openness and Technology

Real exchange rate movements are important drivers of the reallocation of resources between sectors of the economy. Economic theory suggests that the impact of exchange rates should vary with the degree of exposure to international competition and with the technology level. We show that both the degree of openness and the technology level mediate the impact of exchange rate movements on labour market developments. According to our estimations, whereas employment in high-technology sectors seems to be relatively immune to changes in real exchange rates, these appear to have sizable and significant effects on highly open low-technology sectors. The analysis of job flows suggests that the impact of exchange rates on these sectors occurs through employment destruction.     

On the relevance of floating exchange rate policies

I study the relevance of the composition of the public debt between domestic and foreign liabilities in a standard stochastic small open-economy framework. The government issues nominal bonds of several maturities with noncontingent face value at redemption. Intervening in the exchange market to implement an adequate state-contingent path for the nominal exchange rate is an effective way for the government to prevent the economy from reaching any competitive equilibrium it wishes to rule out. Most sterilized interventions are not neutral; however, few of them are. As a consequence, the composition in question is undetermined. Hence, a floating regime may decentralize every competitive outcome, even one induced by a pegging policy. Conversely, outcomes brought forth by a floating regime can also be induced by a policy that prescribes active government intervention in the foreign currency market. Moreover, an open-market operation can be replaced by an equivalent combination of an exchange intervention plus a restructuring of the domestic debt maturity. Introducing in the model strategic behavior by the government combined with asymmetric information or lack of commitment can remove that indeterminacy. Hence, these factors seem to be the major determinants of a possible relation between floating exchange rate policies and economic outcomes.     

ESTIMATION OF GLOBAL LOGISTICS EXPENDITURES USING NEURAL NETWORKS

Measuring the size of global logistics expenditure is a difficult task. What is an estimate of logistics expenditures for the global economy? The objective of this research is to answer this question. Using neural networks, an artificial intelligence methodology, logistics expenditures have been estimated at the country level. There are two main contributions from this research. The first is an update of previous estimates of global logistics expenditures. The second is continuous improvement of the estimation method, including information quality and availability as well as mathematical model refinement.