Abstract

This paper proposes a methodology to approximate individual income distribution dynamics using only time series data on aggregate moments of the income distribution. Under the assumption that individual incomes follow a lognormal autoregressive process, this paper shows that the evolution over time of the mean and standard deviation of log income across individuals provides sufficient information to place upper and lower bounds on the degree of mobility in the income distribution. The paper demonstrates that these bounds are reasonably informative, using the U.S. Panel Study of Income Dynamics where the panel structure of the data allows us to compare measures of mobility directly estimated from the micro data with approximations based only on aggregate data. Bounds on mobility are estimated for a large cross-section of countries, using data on aggregate moments of the income distribution available in the World Wealth and Income Database and the World Bank's PovcalNet database. The estimated bounds on mobility imply that conventional anonymous growth rates of the bottom 40 percent (top 10 percent) that do not account for mobility substantially understate (overstate) the expected growth performance of those initially in the bottom 40 percent (top 10 percent). Document type: Book

Abstract

This paper uses a popular web mapping and transportation service to generate information for more than 22 million counterfactual trip instances in 154 large Indian cities. It then develops a methodology to estimate robust indices of mobility for these cities. The estimation allows for an exact decomposition of overall mobility into uncongested mobility and the congestion delays caused by traffic. The paper first documents wide variation in mobility across Indian cities. It then shows that this variation is driven primarily by uncongested mobility. Finally, the paper investigates correlates of mobility and congestion. Denser and more populated cities are slower, in part because of congestion, especially close to their centers. Urban economic development is generally correlated with better uncongested mobility, worse congestion, and overall with better mobility. Document type: Book

Abstract

Traffic-related injuries represent a global public health problem, and contribute largely to mortality and years lived with disability worldwide. Over the course of the last decades, improvements to road traffic safety and injury surveillance systems have resulted in a shift in focus from the prevention of motor vehicle accidents to the control of injury events involving vulnerable road users (VRUs), such as cyclists and moped riders. There have been calls for improvements to the evaluation of safety interventions due to methodological problems associated with the most commonly used study designs. The purpose of this licentiate thesis was to assess the strengths and limitations of the interrupted time series (ITS) design, which has gained some attention for its ability to provide valid effect estimates. Two national road safety interventions involving VRUs were selected as cases: the Swedish bicycle helmet law for children under the age 15, and the tightening of licensing rules for Class 1 mopeds. The empirical results suggest that both interventions were effective in improving the safety of VRUs. Unless other concurrent events affect the treatment population at the exact time of intervention, the effect estimates should be internally valid. One of the main limitations of the study design is the inability to identify why the interventions were successful, especially if they are complex and multifaceted. A lack of reliable exposure data can also pose a further threat to studies of interventions involving VRUs if the intervention can affect the exposure itself. It may also be difficult to generalize the exact effect estimates to other regions and populations. Future studies should consider the use of the ITS design to enhance the internal validity of before-after measurements. Traffic-related injuries represent a global public health problem, and contribute largely to mortality and years lived with disability. Over the course of the last decades, improvements to road traffic safety and injury surveillance systems have resulted in a shift in focus from motor vehicle accidents to injury events involving vulnerable road users (VRUs), such as cyclists and moped riders. There have been calls for improvements to the evaluation of safety interventions due to methodological problems associated with the most commonly used study designs. The purpose of this licentiate thesis was to assess the strengths and limitations of the interrupted time series (ITS) design, which has gained some attention for its ability to provide valid effect estimates while accounting for secular trends. Two national interventions involving VRUs were selected as cases: the Swedish bicycle helmet law for children under the age 15, and the tightening of licensing rules for Class 1 mopeds. The empirical results suggest that both interventions were effective. These results are discussed in the light of some methodological considerations regarding internal and external validity, data quality and the ability to fully understand key causal mechanisms behind complex interventions. 

Abstract

El boletín de la Sociedad Mexicana de Computación Científica y sus Aplicaciones publica artículos de investigación originales y de alta calidad en las áreas computación científica y sus aplicaciones, así como artículos de difusión científica. Todos los artículos son sometidos a una revisión por expertos de instituciones nacionales e internacionales.

El Boletín es una publicación oficial de la Sociedad Mexicana de Computación Científica y sus Aplicaciones.

Las instrucciones y el template para enviar los documentos pueden ser descargados desde la página principal de la Sociedad (https://www.smcca.org.mx/) o haciendo clic en este enlance.

Abstract

Competitiveness of rail transport compared to road transport has been reducing, especially on regional railway lines. To improve this situation, the EU adopted various directives and regulations to increase efficiency of railway undertakings. In this paper we present an organizational and economic model based on European policies for local railway system. The organizational model is based on multi-criteria decision analysis. For the economic model we used an econometric approach to estimate the cost function and marginal costs in regional lines, which constitute the basis for railway charges. By implementing such an organizational model, the functioning of the railway network will improve. The research found that a change in the existing model of calculating costs of infrastructure use would bring economic effects for the railway infrastructure manager and the providers of transport. Using the proposed model we also found that it is reasonable to increase the flow of goods on unused regional railway lines because the railway infrastructure maintenance costs are inelastic with regard to transported gross tons. Konkurentnost željezničkog prijevoza u usporedbi s cestovnim se smanjuje, naročito na regionalnim željezničkim prugama. Kako bi se poboljšala ta situacija, EU je donijela razne direktive i pravila u svrhu povećanja učinkovitosti željezničkih poduzeća. U ovom radu predstavljamo organizacijski i ekonomski model koji se zasniva na europskoj politici vođenja lokalnog željezničkog sustava. Organizacijski model se temelji na analizi odluke o više kriterija. Za ekonomski smo model primijenili ekonometrijski pristup u procjeni funkcije troškova i marginalnih troškova na regionalnim prugama, koji predstavljaju osnovu troškova na željeznici. Primjenom takvog organizacijskog modela, poboljšat će se funkcioniranje željezničke mreže. Istraživanjem se ustanovilo da bi promjena postojećeg modela izračuna troškova korištenja infrastrukture donijela ekonomske koristi rukovodiocu željezničke infrastrukture i onima koji su zaduženi za promet. Primjenom predloženog modela također smo ustanovili da ima smisla povećati protok robe na nekorištenim željezničkim linijama jer su troškovi održavanja željezničke infrastrukture neelastični u odnosu na prevezene bruto tone.

Abstract

The cableway transport system is very important for the Slovenian tourist economy. Within the Slovene transport system, the cableway transport subsystem has a specific role because it allows and ensures access to regions which are difficult to access or completely inaccessible by other transport subsystems owing to the configuration of the area. The quality and development of transport services are directly linked to the introduction of new cableways. New technical achievements, which are nowadays used in cableways, all provide greater capacity and higher speed of cableways, which, however, results in their higher maintenance and exploitation costs. The cableway transport system is being developed in Slovenia, but not on principles of sustainable development. This paper presents a model of sustainable growth and development of the cableway transport system in Slovenia based on which it is possible to determine assumptions for future growth so that the Slovene cableway transport system would approach standards of such highly developed systems. The new model includes ten essential elements of this system for which growth rates were calculated. Žičniški prometni sistem ima v slovenskem turističnem gospodarstvu važno vlogo. V okviru prometnega sistema ima kot prometni podsistem specifično vlogo, saj nudi dostopnosti do krajev, ki so zaradi geografskih značilnosti težko dostopni ali nedostopni z drugimi prometnimi podsistemi. Novi tehnični dosežki, ki se uporabljajo na žičniških napravah omogočajo vse večje hitrosti in kapacitete žičniških naprav, vendar je zaradi vedno več potrebno vlagat v vzdrževanje in obratovanje žičniških naprav Žičniški prometni sistem se v Sloveniji razvija, ampak na načelih trajnostnega razvoja. V tem članku je predstavljen model trajnostne rasti in razvoja žičniškega prometnega sistema v Sloveniji, na osnovi katerega je mogoče določiti predpostavke za bodoči trajnostni razvoj, da bi se slovenski žičniški promet približal standardom visoko razvitih žičniških sistemov. Novi model zajema 10 bistvenih elementov tega sistema, znotraj katerih so podane direktne in indirektne stopnje rasti razvoja.