Regulatory and environmental effects on public transit efficiency: a mixed DEA-SFA approach

This paper assesses the impact of regulatory and environmental factors and statistical noise on the efficiency of public transit systems within a DEA-based framework. Using a panel of Italian companies, we implement a DEA-SFA mixed approach based on [H.O. Fried et al. (2002) Journal of Productivity Analysis, 17(1–2), 157–174] to decompose DEA inefficiency measures into three components: exogenous effects, managerial inefficiency and stochastic events. Besides providing evidence on the determinants of input-specific efficiency differentials across companies, the results point out that managerial skills play a minor role, and emphasize the relevance of regulatory policies aimed at replacing cost-plus subsidization with high-powered incentive contracts as well as improving environmental conditions of public transit networks.      

Economics of externalities and public policy

In this paper we study a particular case of “multiple” externalities associated to the production of a good/activity, whose external effects can change from positive to negative depending on the level of output (intersecting externalities). To analyze their impact on the public policy we propose a very simple two-agent partial equilibrium model in the technological context of externalities. In a static framework, the centralized solution always implies an optimal policy, which may consist of taxation or subsidization depending on the individual optimum and on the technology parameters. In a dynamic model with local knowledge of the efficiency function and instantaneous output adjustments, such an optimal policy can be structurally stable or unstable. In the latter case, under small changes of the parameters the policy may switch from low taxation/subsidization to high taxation/subsidization or vice versa, or even jump discontinuously from taxation to subsidization or vice versa. Furthermore, the decentralized solution based upon “tradable rights” can be economically equivalent to the centralized solution in the form of taxation policy but the two solutions may be not politically equivalent.

Measuring the Underground Economy with the Currency Demand Approach: A Reinterpretation of the Methodology,With an Application to Italy

We contribute to the debate on how to assess the size of the underground (or shadow) economy by proposing a reinterpretation of the traditional Currency Demand Approach (CDA) à la Tanzi. In particular, we introduce three main innovations. First, we take a direct measure of the value of cash transactions—the flow of cash withdrawn from bank accounts relative to total non‐cash payments—as the dependent variable in the money demand equation. This allows us to avoid unrealistic assumptions on the velocity of money and the absence of any irregular transaction in a given year, overcoming two severe critiques to the traditional CDA. Second, in place of the tax burden level, usually intended as the main motivation for non‐compliance, we include among the covariates two direct indicators of detected tax evasion. Finally, we control also for the role of illegal production considering crimes like drug dealing and prostitution, which—jointly with the shadow economy—contributes to the larger aggregate of the non‐observed economy and represents a significant component of total cash payments. We propose then an application of this “modified CDA” to a panel of 91 Italian provinces for the years 2005–08.     

Testing for PPP: Should we use panel methods?

A common finding in the empirical literature on the validity of purchasing power parity (PPP) is that it holds when tested for in panel data, but not in univariate (i.e. country-specific) analysis. The usual explanation for this mismatch is that panel tests for unit roots are more powerful than their univariate counterparts. In this paper we suggest an alternative explanation. Existing panel methods assume that cross-unit cointegrating relationships, that would tie the units of the panel together, are not present. Using simulations, we show that if this important underlying assumption of panel unit root tests is violated, the empirical size of the tests is substantially higher than the nominal level, and the null hypothesis of a unit root is rejected too often even when it is true. More generally, this finding warns against the automatic use of panel methods for testing for unit roots in macroeconomic time series.First version received: November 2001/Final version received : October 2003     

Ambiguous events and maxmin expected utility

We study the properties associated to various definitions of ambiguity [L.G. Epstein, J. Zhang, Subjective probabilities on subjectively unambiguous events, Econometrica 69 (2001) 265-306; P. Ghirardato et al., Differentiating ambiguity and ambiguity attitude, J. Econ. Theory 118 (2004) 133-173; K. Nehring, Capacities and probabilistic beliefs: a precarious coexistence, Math. Soc. Sci. 38 (1999) 197-213; J. Zhang, Subjective, ambiguity, expected utility and Choquet expected utility, Econ. Theory 20 (2002) 159-181] in the context of Maximin Expected Utility (MEU). We show that each definition of unambiguous events produces certain restrictions on the set of priors, and completely characterize each definition in terms of the properties it imposes on the MEU functional. We apply our results to two open problems. First, in the context of MEU, we show the existence of a fundamental incompatibility between the axiom of “Small unambiguous event continuity” (Epstein and Zhang, 2001) and the notions of unambiguous event due to Zhang (2002) and Epstein and Zhang (2001). Second, we show that, in the context of MEU, the classes of unambiguous events according to either Zhang (2002) or Epstein and Zhang (2001) are always λ-systems. Finally, we reconsider the various definitions in light of our findings, and identify some new objects (Z-filters and EZ-filters) corresponding to properties which, while neglected in the current literature, seem relevant to us.     

Environmental Kuznets Curves for Air Pollutant Emissions in Italy: Evidence from Environmental Accounts (NAMEA) Panel Data

This paper provides new empirical evidence on delinking and Environmental Kuznets Curves (EKC) for greenhouse gases and other air pollutant emissions in Italy. A panel dataset based on the Italian NAMEA (National Accounts Matrix including Environmental Accounts) for 1990–2001 is analysed. The highly disaggregated dataset (29 production branches, 12 years and nine air emissions) provides a large heterogeneity and can help to overcome the shortcomings of the usual approach to EKC based on cross-country data. Both value added and capital stock per employee are used as alternative drivers for analysing sectoral NAMEA emissions. Trade openness at the same sectoral level is also introduced among the covariates. We find mixed evidence supporting the EKC hypothesis. The analysis of NAMEA-based data shows that some of the pollutants such as two greenhouse gases (CO₂ and CH₄) and CO, produce inverted U-shaped curves with coherent within-range turning points. Other pollutants (SO_X, NO_X, PM₁₀) show a monotonic or even N-shaped relationship. Macro sectoral disaggregated analysis highlights that the aggregated outcome should hide some heterogeneity across different groups of production branches (industry, manufacturing only and services). Services tend to present an inverted N-shape in most cases. Manufacturing industry shows a mix of inverted U and N-shapes, depending on the emission considered. The same is true for industry (all industries, not only manufacturing): although a turning point has been experienced, N-shapes may lead to increased emissions with respect to very high levels of the economic driver. In general, EKC evidence is more pronounced for greenhouse gases. The results suggest that analysis at macro sector (whole industry, manufacturing only and services) can be the most promising approach to future research on EKC.     

The bargaining set of a large game

We study the equivalence between the Mas-Colell bargaining set and the core in the general context of TU games with a measurable space of players. In the first part of the paper, we study the problem without imposing any restriction on the class of games we consider. In the second part, we first introduce a new class of exact games, which we call thin games. For these games, we show not only that the Mas-Colell bargaining set is equal to the core, but also that it is the unique stable set in the sense of von Neumann and Morgenstern. We then study the relation between thin games, exact non-atomic market games and non-atomic convex games. Finally, by further developing “thinness” related ideas, we prove new equivalence results for a class of non-exact market games as well as a class of non-exact, non-market games.     

The reliability of real-time estimates of the euro area output gap

This paper provides evidence on the reliability of euro area real-time output gap estimates. A genuine real-time data set for the euro area is used, including vintages of several sets of euro area output gap estimates available from 1999 to 2010. It turns out that real-time estimates of the output gap tend to be characterised by a high degree of uncertainty, much higher than that resulting from model and estimation uncertainty only. In particular, the evidence indicates that both the magnitude and the sign of the real-time estimates of the euro area output gap are very uncertain. The uncertainty is mostly due to parameter instability and model uncertainty, while data revisions seem to play a minor role. Some euro area real-time measures, based on multivariate components models and capacity utilisation, are relatively less uncertain, but do not appear to be fully reliable along some dimensions. To benchmark our results, we repeat the analysis for the US over the same sample. It turns out that US real-time estimates tend to be revised to a lesser extent than euro area estimates. However, euro area real-time output gap estimates tend to display a higher correlation with the final estimates and the sign of the level of US real-time estimates tends to be revised more often compared to the corresponding euro area estimates. In addition, the data revision component of the revision error is larger for US estimates than for the euro area. Overall, the unreliability in real-time of the US output gap measures detected in earlier studies is confirmed in the more recent period.