Null models of economic networks: the case of the world trade web

In all empirical-network studies, the observed properties of economic networks are informative only if compared with a well-defined null model that can quantitatively predict the behavior of such properties in constrained graphs. However, predictions of the available null-model methods can be derived analytically only under assumptions (e.g., sparseness of the network) that are unrealistic for most economic networks like the world trade web (WTW). In this paper we study the evolution of the WTW using a recently-proposed family of null network models. The method allows to analytically obtain the expected value of any network statistic across the ensemble of networks that preserve on average some local properties, and are otherwise fully random. We compare expected and observed properties of the WTW in the period 1950–2000, when either the expected number of trade partners or total country trade is kept fixed and equal to observed quantities. We show that, in the binary WTW, node-degree sequences are sufficient to explain higher-order network properties such as disassortativity and clustering-degree correlation, especially in the last part of the sample. Conversely, in the weighted WTW, the observed sequence of total country imports and exports are not sufficient to predict higher-order patterns of the WTW. We discuss some important implications of these findings for international-trade models.     

The covariation for Banach space valued processes and applications

This article focuses on a recent concept of covariation for processes taking values in a separable Banach space $B$ and a corresponding quadratic variation. The latter is more general than the classical one of Métivier and Pellaumail. Those notions are associated with some subspace $\chi $ of the dual of the projective tensor product of $B$ with itself. We also introduce the notion of a convolution type process, which is a natural generalization of the Itô process and the concept of $\bar{\nu }_0$ -semimartingale, which is a natural extension of the classical notion of semimartingale. The framework is the stochastic calculus via regularization in Banach spaces. Two main applications are mentioned: one related to Clark–Ocone formula for finite quadratic variation processes; the second one concerns the probabilistic representation of a Hilbert valued partial differential equation of Kolmogorov type.     

Closed-skew normality in stochastic frontiers with individual effects and long/short-run efficiency

This paper considers the estimation of Kumbhakar et al. (J Prod Anal. doi:10.1007/s11123-012-0303-1, 2012) (KLH) four random components stochastic frontier (SF) model using MLE techniques. We derive the log-likelihood function of the model using results from the closed-skew normal distribution. Our Monte Carlo analysis shows that MLE is more efficient and less biased than the multi-step KLH estimator. Moreover, we obtain closed-form expressions for the posterior expected values of the random effects, used to estimate short-run and long-run (in)efficiency as well as random-firm effects. The model is general enough to nest most of the currently used panel SF models; hence, its appropriateness can be tested. This is exemplified by analyzing empirical results from three different applications.     

Analytic derivatives and the computation of GARCH estimates

In the context of univariate GARCH models we show how analytic first and second derivatives of the log-likelihood can be successfully employed for estimation purposes. Maximum likelihood GARCH estimation usually relies on the numerical approximation to the log-likelihood derivatives, on the grounds that an exact analytic differentiation is much too burdensome. We argue that this is not the case and that the computational benefit of using the analytic derivatives (first and second) may be substantial. Furthermore, we make a comparison of various gradient algorithms that are used for the maximization of the GARCH Gaussian likelihood. We suggest the implementation of a globally efficient computation algorithm that is obtained by suitably combining the use of the estimated information matrix with that of the exact Hessian during the maximization process. As this would appear a straightforward extension, we then study the finite sample performance of the exact Hessian and its approximations (that is, the estimated information, outer products and misspecification robust matrices) in inference.     

Relational Contracting in Developed Economies: Lessons From Slot Exchanges in the US Airline Industry

This paper highlights the widespread use of relational contracting in developed economies. While the number of empirical studies on relational practices in developing countries is increasing rapidly, evidence from industries and countries characterised by strong institutions is lagging behind due to data constraints. We argue that technological progress and strong institutions do not diminish the use of relational contracting, and use the US airline industry as a case in point. In particular, we discuss a number of factors (including transaction complexity, existence of collaborative relationships and data availability) that make this industry an ideal setting to study relational contracting in a developed economy. Moreover, we argue that other industries in developed countries share the properties of the US airline industry and, hence, can be used as a basis to investigate relational contracting in future work.     

The demand-boost theory of exclusive dealing

This article unifies various approaches to the analysis of exclusive dealing that so far have been regarded as distinct. The common element of these approaches is that firms depart from efficient pricing, raising marginal prices above marginal costs. We show that with distorted prices, exclusive dealing can be directly profitable and anticompetitive provided that the dominant firm enjoys a competitive advantage over rivals. The dominant firm gains directly, rather than in the future, or in adjacent markets, thanks to the boost in demand it enjoys when buyers sign exclusive contracts. We discuss the implication of the theory for antitrust policy.     

Characterizing the mission statements of benefit corporations: Empirical evidence from Italy

In 2015, Italy introduced a new legal form—“benefit corporation” (società benefit)—that provides legal status to companies that have one or more common benefit objectives in addition to the profit-seeking goal. Italian benefit corporations are obligated by law to operate in a responsible, sustainable, and transparent way and to include the interests of different stakeholders in their corporate strategy. This study examines the Italian case by applying textual statistical analysis on benefit corporations' public mission statements using the IRaMuTeQ software. Performing hierarchical cluster analysis and correspondence factor analysis identifies the “benefit” concept emerging from the mission statements in terms of promotion of individual skills, development of a new business model, and service to society. This study contributes to the debate on the content of mission statements by giving empirical evidence about this new form of business, and it provides some practical implications for managers, entrepreneurs, and policymakers.     

Immigration Policy,Self‐selection,and the Quality of Immigrants*

This paper investigates the effects of immigration quotas on the average quality of immigrants by developing a human capital migration model where efficiency in migration depends on skills and emigration rates are higher among skilled workers. Studying the joint determination of the domestic level of wages and immigrants' self‐selection, we find a negative relationship between the wage level and the percentage of educated workers among immigrants, which results in a nonstandard downward‐sloping labor supply. In our framework, a higher quota increases the skill mix of immigrants through its negative effect on wages and raises aggregate national income.     

Equilibrio e relazione distributiva in un modello di Sraffa con tassi di profitto eterogenei

Si considera un modello di Sraffa a produzione semplice nel quale l'ipotesi di uniformità del saggio di profitto è sostituita con quella di saggi di profitto eterogenei ma in rapporto costante tra di loro. Per tale modello vengono studiati l'esistenza di soluzioni, la costanza dei prezzi rispetto alle variabili distributive ed il legame funzionale tra queste, con speciale riguardo al caso lineare.

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Summary This note deals with the well-known Sraffa's model of exchange for a simple production economy in the case where the sector profit rates bear constant proportions to each other. Some formal results are presented on the equilibria of the model, both in normal and in vertical integrated form, on the dependence, implicitly defined by the model, of the prices vector and of the wage rate on the profit parameter, and about the concepts of (generalized) standard productions and uniform composition of capital.