Revisiting Savage in a conditional world

Summary. I present an axiomatization of subjective expected utility and Bayesian updating in a conditional decision problem. This result improves our understanding of the Bayesian standard from two perspectives: 1) it uses a set of axioms which are weak and intuitive; 2) it provides a formal proof to results on the relation between dynamic consistency, expected utility and Bayesian updating which have never been explicitly proved in a fully subjective framework. Received: December 1, 2000; revised version: February 26, 2001     

Regression density estimation using smooth adaptive Gaussian mixtures

We model a regression density flexibly so that at each value of the covariates the density is a mixture of normals with the means, variances and mixture probabilities of the components changing smoothly as a function of the covariates. The model extends the existing models in two important ways. First, the components are allowed to be heteroscedastic regressions as the standard model with homoscedastic regressions can give a poor fit to heteroscedastic data, especially when the number of covariates is large. Furthermore, we typically need fewer components, which makes it easier to interpret the model and speeds up the computation. The second main extension is to introduce a novel variable selection prior into all the components of the model. The variable selection prior acts as a self-adjusting mechanism that prevents overfitting and makes it feasible to fit flexible high-dimensional surfaces. We use Bayesian inference and Markov Chain Monte Carlo methods to estimate the model. Simulated and real examples are used to show that the full generality of our model is required to fit a large class of densities, but also that special cases of the general model are interesting models for economic data.     

Community structure in the World Trade Network based on communicability distances

In this paper, we investigate the mesoscale structure of the World Trade Network. In this framework, a specific role is assumed by short- and long-range interactions, and hence by any suitably defined network-based distance between countries. Therefore, we identify clusters through a new procedure that exploits Estrada communicability distance and the vibrational communicability distance, which turn out to be particularly suitable for catching the inner structure of the economic network. The proposed methodology aims at finding the distance threshold that maximizes a specific quality function defined for general metric spaces. Main advantages regard the computational efficiency of the procedure as well as the possibility to inspect intercluster and intracluster properties of the resulting communities. The numerical analysis highlights peculiar relationships between countries and provides a rich set of information that can hardly be achieved within alternative clustering approaches.

     

A comparison of different trading protocols in an agent-based market

We compare price dynamics of different market protocols (batch auction, continuous double auction and dealership) in an agent-based artificial exchange. In order to distinguish the effects of market architectures alone, we use a controlled environment where allocative and informational issues are neglected and agents do not optimize or learn. Hence, we rule out the possibility that the behavior of traders drives the price dynamics. Aiming to compare price stability and execution quality in broad sense, we analyze standard deviation, excess kurtosis, tail exponent of returns, volume, perceived gain by traders and bid-ask spread. Overall, a dealership market appears to be the best candidate, generating low volume and volatility, virtually no excess kurtosis and high perceived gain.     

Trust,risk and time preferences: evidence from survey data

The paper shows that time preferences and risk preferences are key covariates of self-reported trust. They both predict negatively a measure of generalized trust; however, risk aversion is positively correlated with an index of particularized trusting behaviour (which refers to the circle of known people).     

Eco‐labelling by a for‐profit certifier: Countervailing power and its consequences

For‐profit certifier's eco‐labelling is common in industries where firms have some “countervailing power” on sharing gains from labelling. We show that the certification standard for an environmental quality is lowered when firms have strong “power.” A certifier with too low bargaining power will prefer to sell to the best offer rather than bargain. This switch in the selling mechanism also thwarts his incentives in setting the standard. This is consequential for evaluating policies. The dimensions and even signs of welfare changes induced by taxes and subsidies depend upon the mechanism used, and ultimately upon firms’ countervailing power.     

Identifying bank outputs and inputs with a directional technology distance function

The bank efficiency literature lacks an agreed definition of bank outputs and inputs. This is problematic given the long-standing controversy concerning the status of deposits, but also because bank efficiency estimates are known to be affected by the inclusion of additional outputs such as non-traditional (fee-based) activities or risk measures. This paper proposes a data-driven identification of bank outputs and inputs using the directional technology distance function. While previous applications of this tool used symmetric expansion or contraction directions, we focus on a set of orthogonal directions, each corresponding to an assumption on the input/output status of an individual variable. These directions correspond to a set of different specifications, whose estimated coefficients can be used to determine the input or output status of all variables except the regressand. Our empirical analysis revealed a very consistent pattern across the alternative specifications estimated. There is strong evidence that customer deposits are an input, and that non-performing loans are an important undesirable output. Finally, the orthogonal expansions/contractions we consider avoid the simultaneity problem raised by the “convenient normalization” commonly used to impose linear homogeneity in stochastic frontier estimation.     

WELFARE ENHANCING COORDINATION IN CONSUMER COOPERATIVES UNDER MIXED OLIGOPOLY

The recent globalization of world economies has led the retail markets of developed countries towards increasing levels of integration and strategic interdependence. A non negligible share of retail and food markets is currently served by co‐operative societies. Consistently with this trend, the consumer cooperatives have recently experienced increasing levels of integration. The main aim of this paper is to study the welfare effects of coordination among consumer cooperatives competing in quantities in a mixed oligopoly against profit‐maximizing firms. We show that, in absence of agency problems, under increasing or constant returns to scale a higher output coordination of the consumer cooperatives does not affect the total welfare as long as a nonnegative profit constraint holds in these firms. On the other hand, under decreasing returns to scale, the consumer cooperatives contribute more to social welfare when acting on behalf of all consumers. This is because, by coordinating consumers’ preferences, these firms can reduce their market output, thus helping the market to come closer to the first best. All together these results seem to provide an argument in favour of the recent process of integration involving consumer cooperatives in many developed countries.     

Fiscal Balance and Current Account in Professional Forecasts

This paper investigates the relationship between financial institutions' expectations of the current account and the fiscal balance. Using professional macroeconomic forecasts for the G‐7 countries, we find a positive relationship between forecasts of the cyclically adjusted fiscal balance deficit and forecasts of the current account deficit, indicating that professional forecasts embody links implied by the twin deficits hypothesis. In assessing the relationship between the forecasts of the fiscal deficit and the current account, we find that forecasters correctly make the distinction between the effect of fiscal policy and automatic stabilizers.