Cross-section data, disequilibrium situations and estimated coefficients: evidence from car ownership demand

The objective of this paper is to analyse to what extent the use of cross-section data will distort the estimated elasticities for car ownership demand when the observed variables do not correspond to a state equilibrium for some individuals in the sample. Our proposal consists of approximating the equilibrium values of the observed variables by constructing a pseudo-panel data set which entails averaging individuals observed at different points of time into cohorts. The results show that individual and aggregate data lead to almost the same value for income elasticity, whereas with respect to working adult elasticity the similarity is less pronounced.Cross-section, Pseudo panel, Disequilibrium.

Traffic forecasts under uncertainty and capacity constraints

Traffic forecasts provide essential input for the appraisal of transport investment projects. However, according to recent empirical evidence, long-term predictions are subject to high levels of uncertainty. This paper quantifies uncertainty in traffic forecasts for the tolled motorway network in Spain. Uncertainty is quantified in the form of a confidence interval for the traffic forecast that includes both model uncertainty and input uncertainty. We apply a stochastic simulation process based on bootstrapping techniques. Furthermore, the paper proposes a new methodology to account for capacity constraints in long-term traffic forecasts. Specifically, we suggest a dynamic model in which the speed of adjustment is related to the ratio between the actual traffic flow and the maximum capacity of the motorway. This methodology is applied to a specific public policy that consists of suppressing the toll on a certain motorway section before the concession expires.

Hedonic prices for cars: an application to the Spanish car market, 1981-2005

In this paper we provide a comparison of different formulations for hedonic regression analysis in order to construct a quality-adjusted price index for the Spanish car market over the period 1981-2005. Specifically, we address the issue of instability of coefficients over time, and propose two alternative estimation procedures based, firstly, on a moving sample of observations and, secondly, on a moving average of estimated coefficients in single period equations. The statistical tests applied support the proposed methodologies. On empirical grounds two conclusions can be emphasised. Firstly, our study concludes that, taking quality changes into account, car prices in Spain deflated by CPI declined by 40% between 1981 and 2005. This result is robust to the alternative estimation procedures employed in the study. Secondly, an analysis of sigma-convergence shows that for quality-adjusted prices a clear trend in σ-convergence emerges between 1986 and 1992, whereas such a trend does not exists for observed prices. This result has to be related to Spain’s integration into the European Comunity

A chemical survey of exoplanets with ARIEL

Thousands of exoplanets have now been discovered with a huge range of masses, sizes and orbits: from rocky Earth-like planets to large gas giants grazing the surface of their host star. However, the essential nature of these exoplanets remains largely mysterious: there is no known, discernible pattern linking the presence, size, or orbital parameters of a planet to the nature of its parent star. We have little idea whether the chemistry of a planet is linked to its formation environment, or whether the type of host star drives the physics and chemistry of the planet’s birth, and evolution. ARIEL was conceived to observe a large number (~1000) of transiting planets for statistical understanding, including gas giants, Neptunes, super-Earths and Earth-size planets around a range of host star types using transit spectroscopy in the 1.25–7.8 μm spectral range and multiple narrow-band photometry in the optical. ARIEL will focus on warm and hot planets to take advantage of their well-mixed atmospheres which should show minimal condensation and sequestration of high-Z materials compared to their colder Solar System siblings. Said warm and hot atmospheres are expected to be more representative of the planetary bulk composition. Observations of these warm/hot exoplanets, and in particular of their elemental composition (especially C, O, N, S, Si), will allow the understanding of the early stages of planetary and atmospheric formation during the nebular phase and the following few million years. ARIEL will thus provide a representative picture of the chemical nature of the exoplanets and relate this directly to the type and chemical environment of the host star. ARIEL is designed as a dedicated survey mission for combined-light spectroscopy, capable of observing a large and well-defined planet sample within its 4-year mission lifetime. Transit, eclipse and phase-curve spectroscopy methods, whereby the signal from the star and planet are differentiated using knowledge of the planetary ephemerides, allow us to measure atmospheric signals from the planet at levels of 10–100 part per million (ppm) relative to the star and, given the bright nature of targets, also allows more sophisticated techniques, such as eclipse mapping, to give a deeper insight into the nature of the atmosphere. These types of observations require a stable payload and satellite platform with broad, instantaneous wavelength coverage to detect many molecular species, probe the thermal structure, identify clouds and monitor the stellar activity. The wavelength range proposed covers all the expected major atmospheric gases from e.g. H2O, CO2, CH4 NH3, HCN, H2S through to the more exotic metallic compounds, such as TiO, VO, and condensed species. Simulations of ARIEL performance in conducting exoplanet surveys have been performed – using conservative estimates of mission performance and a full model of all significant noise sources in the measurement – using a list of potential ARIEL targets that incorporates the latest available exoplanet statistics. The conclusion at the end of the Phase A study, is that ARIEL – in line with the stated mission objectives – will be able to observe about 1000 exoplanets depending on the details of the adopted survey strategy, thus confirming the feasibility of the main science objectives.Peer reviewedFinal Published versio

Job Accessibility and Female Employment Probability: The Cases of Barcelona and Madrid

The objective of this paper is to estimate the impact of residential job accessibility on female employment probability in the metropolitan areas of Barcelona and Madrid. Following a 'spatial mismatch' framework, a female employment probability equation is estimated which includes variables controlling for personal characteristics, residential segregation and employment potential by public transport network. Data used come from the Micro-census 2001 of INE (the National Institute of Statistics). The research focuses on the treatment of endogeneity problems and the measurement of accessibility variables. The results show that low job accessibility in public transport negatively affects employment probability. The intensity of this effect tends to decrease with individual's educational attainment. A higher degree of residential segregation also reduces job probability in a significant way.

Changes in the structure of car ownership in Spain

This paper analyses the factors determining the growth in car ownership in Spain over the last two decades. A discrete choice model is estimated at three points in time: 1980, 1990 and 2000. The paper compares the two alternative decision mechanisms used for modelling car ownership: ordered-response versus unordered-response mechanisms and concludes that on the basis of forecasting performance, the multinomial logit model and the ordered probit model are almost undistinguishable. The empirical results show that income elasticity is not constant and declines as car ownership increases. Besides, households living in rural areas are less income sensitive than those living in urban areas. Car ownership is also sensitive to the quality of public transport for those living in the largest cities. The results also confirm the existence of a generation effect, which will vanish around the year 2020, a weak life-cycle effect, and a positive effect of employment on the number of cars per household. Finally, the change in the estimated coefficients over time reflects an increase in mobility needs and, consequently, an increase in car ownership. The study also quantifies the relative importance of each explanatory factor to car ownership growth

Changes in the structure of car ownership in Spain

This paper analyses the factors determining the growth in car ownership in Spain over the last two decades. A discrete choice model is estimated at three points in time: 1980, 1990 and 2000. The paper compares the two alternative decision mechanisms used for modelling car ownership: ordered-response versus unordered-response mechanisms and concludes that on the basis of forecasting performance, the multinomial logit model and the ordered probit model are almost undistinguishable. The empirical results show that income elasticity is not constant and declines as car ownership increases. Besides, households living in rural areas are less income sensitive than those living in urban areas. Car ownership is also sensitive to the quality of public transport for those living in the largest cities. The results also confirm the existence of a generation effect, which will vanish around the year 2020, a weak life-cycle effect, and a positive effect of employment on the number of cars per household. Finally, the change in the estimated coefficients over time reflects an increase in mobility needs and, consequently, an increase in car ownership. The study also quantifies the relative importance of each explanatory factor to car ownership growth.

Infraestructura viària, inversió privada i PIB per càpita

Aquest treball estima l’impacte que una millora en la xarxa viària té en la inversió en béns d’equipament, distingint segons el nivell de PIB per càpita de cada territori. S’utilitzen dades agregades per 48 províncies observades entre 1977 i 2008. Els resultats mostren que una millora en la infraestructures té un impacte positiu en el creixement econòmic d’un territori que és tan més alt com més alt és el seu nivell de renda. Així mateix, es proposa un sistema d’equacions que permet aproximar l’impacte a llarg termini d’una infraestructura en el PIB. En relació amb aquest últim punt es presenta evidencia per Barcelona, Girona, Tarragona i Lleida

Regional infrastructure investment and efficiency

<p>Using Spanish data, this paper shows that improvements in the road network have a positive effect on private investment in capital assets, and this effect increases with the level of economic development of a geographical area. We use aggregate data at the provincial level between the years 1977–2008. Additionally, we propose a system of equations in order to approximate the long-run effects. We find statistical evidence of efficiency loss associated with the distributional aims of the infrastructure policy. More importantly, since the effects of infrastructure investment are permanent, in the long run, efficiency costs will be higher.</p