An integrated algorithm for three-way compositional data

Quality & Quantity - Compositional data with a tridimensional structure are not uncommon in social sciences. The CANDECOMP/PARAFAC model is one of the most adequate techniques for modeling...     

A fuel surcharge policy for reducing road traffic greenhouse gas emissions

This paper proposes a car pricing policy based on fuel surcharges in substitution of car ownership taxes for reducing greenhouse gas emissions by cars. The aim of the proposed policy is to change some (fixed) costs of car use that are not perceived at each trip into (variable) costs. The amount of fuel surcharges and the effects of their application on fuel consumption and on GHG emissions are estimated by a model that is able to relate gasoline and diesel consumption with fuel prices. The effects of the proposed policy on fuel consumption and on GHG emissions are estimated for Italy. The results show that car users prefer to shift towards more efficient fuel vehicles than to public transport, producing a significant, but less than expected, reduction of GHG emissions.     

Lending technologies,banking relationships,and firms’ access to credit in Italy: the role of firm size

This paper analyses the role of lending technologies and banking relationships on firms’ credit access in Italy. Using EFIGE firm-level data, we show that the depth and strength of firm–bank relationships have heterogeneous effects on credit demand and rationing probabilities depending on the size of the borrower. Multiple banking relationships alleviate financial constraints for small firms, while borrowing from a large number of lenders hinders access to credit for large companies. Small and medium-sized enterprises with a higher share of debt with the main bank have a lower probability of being credit denied, as debt concentration contributes to overcome the opacity problems typical of the SMEs. Long-lasting relationships, by reducing information asymmetries, significantly improve access to credit for small and large firms. Conversely, we find that medium-sized enterprises are more exposed to financing constraints as relationship duration increases, due to possible lock-in effects. Finally, firms maintaining banking relationships based on transactional technologies are more likely to be credit denied, while the use of relationship lending technologies improves credit availability for both small and large enterprises.     

SEMIPARAMETRIC VECTOR MEM

Financial time series are often non‐negative‐valued (volumes, trades, durations, realized volatility, daily range) and exhibit clustering. When joint dynamics is of interest, the vector multiplicative error model (vMEM; the element‐by‐element product of a vector of conditionally autoregressive scale factors and a multivariate i.i.d. innovation process) is a suitable strategy. Its parameters can be estimated by generalized method of moments, bypassing the problem of specifying a multivariate distribution for the errors. Simulated results show the gains in efficiency relative to an equation‐by‐equation approach. A vMEM on several measures of volatility justifies a joint approach revealing full interdependence. Copyright © 2012 John Wiley & Sons, Ltd.     

The social costs of monopoly?

The essay recounts the contributions of earlier economists to the discussion of the social costs of monopoly. They largely duplicate more contemporary contributions.     

Reoptimization procedures in shortest path problem

In most algorithms for Transportation and Communication Models a sequence of Shortest Path Problems must be solved, where each problem is only slightly different from the preceding. Computational procedures are proposed to find the new shortest paths starting from the old shortest paths in two cases: i) the node from which the shortest paths are to be determined is changed; ii) the cost of one are is modified (either increased or decreased).This research was partially done while the author was visting the Centre de Recherche sur les Transports, Université de Montréal, with a financial support of the National Research Council of Italy.     

A multilayer model to simulate cruising for parking in urban areas

In this paper we propose an assignment model on urban networks to simulate parking choices; this model is able to simulate the impact of cruising for parking on traffic congestion. For simulating parking choice and estimating the impact of cruising on road congestion we propose a multi-layer network supply model, where each layer simulates a trip phase (on-car trip between the origin and destination zone, cruising for parking at destination zone and walking egress trip). In this model the cruising time is explicitly simulated on the network. The proposed model is tested on a trial network and on a real-scale network; numerical tests highlighted that the proposed model is able to simulate user parking choice behaviour and the impact of cruising for parking upon road congestion, particularly when the average parking saturation degrees exceed 0.7.     

REGULATION OF POLLUTION IN THE LABORATORY: RANDOM INSPECTIONS,AMBIENT INSPECTIONS,AND COMMITMENT PROBLEMS

We compare experimentally a traditional random inspection policy and a variant where the agency may carry out a preliminary inspection of the level of ambient pollution before implementing any individual inspection. Since the agency may have an incentive to announce high inspection probabilities and then secretly renege on its announcement to avoid implementing costly inspections, we are also interested in the agency's commitment power. We find that overall, ambient inspections increase efficiency but the effect is weaker than expected when the agency has no commitment power; and polluters' reactions to the lack of commitment power of the agency vary depending on whether the agency uses ambient inspections or not.