Papers by Sergio Jara-Diaz
Analisis Comparativo De Modelos De Uso De Tiempo
El propósito de los modelos de uso de tiempo es explicar el tiempo asignado a las actividades en ... more El propósito de los modelos de uso de tiempo es explicar el tiempo asignado a las actividades en función de variables independientes. Existen muchos enfoques para estudiar el uso y el valor del tiempo; cada uno de ellos tiene fortalezas y debilidades, generando diferentes resultados y conclusiones que hasta el momento se han estudiado por separado. La idea de esta tesis es aplicar, mejorar y comparar diferentes enfoques usando la misma información. Primero se identifican aquellos enfoques que están más robustamente justificados, ya sea por su base teórica o su fundamento empírico-estadístico. Luego se proponen modelos que representan la esencia de cada enfoque y se estiman utilizando los métodos más avanzados: modelos de ecuaciones estructurales, modelos microeconómicos y modelos de ecuaciones de tiempo. La información utilizada proviene de datos de uso de tiempo y gastos de Santiago (Chile) y los Estados Unidos de América. Para hacerlos comparables, cada enfoque ha sido modificado en las formas que se indican a continuación. Se estima un modelo de ecuaciones estructurales que mantiene las características genéricas de este enfoque cuando se aplica a uso de tiempo, pero se incorpora además de actividades y variables socioeconómicas, gastos en la modelación (productor de la interacción con un grupo de investigación de Arizona State University). Las variables endógenas son tiempo de trabajo, tiempo de recreación y gasto en recreación. Las variables explicativas son edad, ingreso, tiempo comprometido (obligado e irreducible) y gasto comprometido. Estas variables son inspiradas en el modelo microeconómico explicado a continuación. La nueva ecuación de gasto en una actividad de ocio permite el cálculo de una disposición a pagar revelada por ocio (DPOR), la cual resulta ser teóricamente diferente al valor del ocio del modelo microeconómico. También se estima un modelo microeconómico siguiendo el propuesto por Jara-Díaz y Guerra (2003), generando un sistema de ecuaciones para el tiempo de trabajo, el tiempo asignado en el hogar y el gasto asociado a la recreación fuera del hogar. Este sistema permite el cálculo de los valores del ocio y el trabajo para diferentes segmentos de la población según edad, género, raza y zona de residencia. El modelo está basado en una función de utilidad del tipo Cobb-Douglas, pero enriquecida por la presencia de dos conceptos además de la tasa salarial: gasto y tiempo comprometido. La diferencia entre la DPOR y el valor del ocio microeconómico es explicada téoricamente mostrando que la DPOR es sólo una componente del valor total del ocio. Finalmente se estima un modelo de ecuaciones de tiempo, explicando el tiempo asignado a actividades discrecionales, siguiendo la forma típica propuesta por Kitamura (1984). Los resultados empíricos y sus fundamentos teóricos muestran que si se trata de manera adecuada las variables y los datos, es posible que dos enfoques que parecían muy diferentes- microeconómico y estructural- convergen en cuanto al uso de tiempo y su valor. El nuevo concepto de disposición a pagar revelada por ocio aparece como una herramienta teórica muy útil
Journal of Transport Geography, 2021
We analyze the spatially distributed impacts of transport investment in urban highways and public... more We analyze the spatially distributed impacts of transport investment in urban highways and public transport with a novel methodology based on the capabilities of online technology to replicate the (unobserved) condition without highways. This is based upon the intensive use of Google Maps API (GMA) to obtain travel times between each origin-destination pair at a highly detailed level to reveal the effects of new infrastructure on different zones and groups within a city. Santiago is used as a case study, as the city introduced 150 km of urban highways, a reorganization of surface transit, and new subway lines in a relatively short period. We show that the highincome segment of the population has been the most favored, simultaneously increasing the difference between transit and car travel times in those areas where car ownership is low, stimulating the acquisition of a car.
Transport Economic Theory, 2007
Structure, Functioning and Regulation of the Spanish Electricity Sector. The Legal Framework and the New Proposals for Reform
Contributions to Economics, 2002
An electrical system consists of a series of distinct stages: generation, transmission, distribut... more An electrical system consists of a series of distinct stages: generation, transmission, distribution and supply (merchandising) of electricity services to the end-users. The traditional organisational model assumes, implicitly or explicitly, the extension of a natural monopoly condition from ...
Aunque la congestión y los problemas medioambientales hacen del aumento de usuarios de transporte... more Aunque la congestión y los problemas medioambientales hacen del aumento de usuarios de transporte público uno de los objetivos declarados más comunes en políticas de transporte urbano, las medidas para lograrlo suelen ser menos exitosas de lo esperado, incluso contraproducentes. En este artículo establecemos relaciones teóricas entre diversos tipos de elasticidades y revisamos exhaustivamente la evidencia empírica, lo que permite entender mejor de qué forma la demanda por transporte público (D TP) es afectada por diversas variables. Salvo para la tarifa, cuya elasticidad de corto plazo se estima entre-0,2 y-0,6, por lo general no se encuentran en la literatura valores suficientemente robustos como para generalizarlos. Aunque la evidencia es escasa, se reconoce la importancia de variables como la confiabilidad, frecuencia, transbordos, estructura tarifaria, ingreso, desempleo y motorización, avalada por algunas experiencias exitosas en ciudades europeas que han logrado aumentar su D TP. Análisis teóricos permiten revelar efectos no inmediatos que variables como el ingreso tienen sobre la D TP .
Preliminary Insights into Optimal Pricing and Space Allocation at Intermodal Terminals with Elastic Arrivals and Capacity Constraint
Networks and Spatial Economics, 2006
Transport Reviews, 2003
After Vickrey's view, Mohring constructed a microeconomic model to determine the optimal frequenc... more After Vickrey's view, Mohring constructed a microeconomic model to determine the optimal frequency of buses serving a corridor with fixed demand. The main result was that frequency should be proportional to the square root of demand. The role of users' costs was shown to be crucial. This approach has evolved over the past decades, improving our understanding of public transport operations. This paper describes and analyses the evolution of microeconomic models for the analysis of public transport services with parametric demand, leading towards a more comprehensive one. An indepth review of all the contributions in the academic literature is presented, emphasizing both the treatment of variables and the form of the results mostly in terms of frequency and fleet size. A series of partial new elements is also identified. An extension of Jansson's model for a single period is developed analytically, including the effect of vehicle size on operating costs and the influence of crowding on the value of time. Numerical simulations are used for comparison and analysis. A general model is then proposed where bus operations are optimized accounting for a number of simultaneous relations. Finally, the different models are discussed and compared.
8th INTERNATIONAL CONFERENCE ON SURVEY IN TRANSPORT ANNECY, FRANCE-MAY 25-31, 2008 Building a weekly time use survey from a one day OD survey
WCTR 2007 The unified expanded goods-activities-travel model: theory and results
The Santiago Tasti Survey (Time Assignment Travel and Income)
Estimation of vehicle-specific long run marginal costs for infrastructure user charges
Modelling Time Assigned to Activities: Estimation Possibilities from a General Framework and an Ad-Hoc Database
10th World Conference …, 2004
This paper presents the general framework of a model system involving time assigned to activities... more This paper presents the general framework of a model system involving time assigned to activities, goods consumption and discrete choices, including the discussion of the error structure within econometric possibilities which are sufficiently general. The paper also describes the generation and contents of an experimental database and presents the calibration results of some of the modeling possibilities using this database.
Building a rich activities-travel database from an OD survey
Although an origin destination (OD) survey is devoted to describe in detail the travel pattern in... more Although an origin destination (OD) survey is devoted to describe in detail the travel pattern in a particular period, the information collected allows recovering, with some level of aggregation, a description of time use of the individuals observed. This allows the possibility to calibrate the time use mode choice model system proposed by Jara-Diaz and Guerra (2003) with a very rich and trustable database. This possibility is explored for the Santiago 2001 OD survey (Ortzar et al, 2003) that has more than 12,000 households sampled randomly from the population of Santiago, each observed during a whole day. As a first stage of this process, we analyze the available information and identify the possible ways to build adequate descriptions of the individuals time assignment to different activities. The sociodemographic characteristics of the sample, which could be used as segmentation variables and to link observations, was also observed. The objective of this work is to obtain from the OD survey, a database similar to one obtained specifically with the purpose of calibrating the time use mode choice model system, which is much smaller in size. The information required to calibrate the time use mode choice model system, and how it can be obtained from the Santiago 2001 OD survey is identified. From this information, we obtain the time allocation to different activities of a representative sample of the inhabitants of Santiago (the OD sample), and analyze the individuals characteristics that influence these time allocations. There are two basic ways to describe the time assignment of a group of individuals: trough the average time assignment and through the activity pattern, that represents the proportion of individuals who are conducting each particular activity at any instant through a period of time, for example a day. Because the OD survey is a travel survey and not a time use survey, the activities can only be obtained through trip purposes, and the degree of aggregation is constrained to the trip purposes included in the OD survey. The detail of what happens inside each of these aggregate activities is not known. The activities that can be deduced from the Santiago OD survey are: stay at home, work (out of home), study (out of home), recreation (out of home), shopping and errands, travel, other activity out of home. As each individual was observed only during one day, the activity patterns of the different days of the week come from different individuals. Although comparisons among days can be made, it would be interesting to build weekly observations through linking observations of very similar individual observed in different days of the week. The analysis is centred on the possibility of aggregating information and generating databases rich in variance, that allow to calibrate the time use mode choice model system, already applied to smaller databases. If we prove it feasible to obtain all the information required from such a large and rich database, we will then count with a very powerful approach to the better understanding of individuals behaviour. For the covering abstract see ITRD E137145.
Acerca De La Enorme Sensibilidad Del Valor Subjetivo Del Tiempo a La Especificación Del Ingreso en La Función De Utilidad
SSRN Electronic Journal, 2005
In this paper we have built a theoretical model using a normalized quadratic cost system to obtai... more In this paper we have built a theoretical model using a normalized quadratic cost system to obtain expressions for actual input demand and cost as functions of three components: frontier, allocative and technical inefficiency. We have used the shadow prices approach in the line of exact decomposition that allows us to solve Greene's problem. Using the normalized quadratic cost system has permited to isolate not only allocative inefficiency but also the technical one, as simple functions of both parameters and variables. The model allows us to obtain individual and time varying technical and allocative inefficency measures when a panel data is available. This model has been applied to cargo handling in Spanish ports.
Adapting Productivity Theory to the Quadratic Cost Function. An Application to the Spanish Electric Sector
Journal of Productivity Analysis, 2003
In this article we have adapted productivity analysis to the case of a cost model using a quadrat... more In this article we have adapted productivity analysis to the case of a cost model using a quadratic cost function and discrete data. The main theoretical result is a productivity index that can be decomposed into modified versions of the contribution of technical change and the effect of the variations in the scale of production. This framework has been applied
Values of work and leisure behind the behaviour of Chilean workers travellers
Transportation Research Part A: Policy and Practice, 2020
Time use models have been used to estimate the value of leisure -one of the components of the val... more Time use models have been used to estimate the value of leisure -one of the components of the value of travel time savings -usually accepting that sleep duration is an exogenous variable. In this paper, we depart from this belief by considering time asleep as an endogenous decision framed by many elements well documented in the literature which we review using a threediscipline perspective: Social behavior sciences, Medical and health sciences, and Economics. Then we propose a microeconomic model that considers these contributions by capturing four effects: alertness (perception), time use trade-off, performance (productivity) and a series of technical relations linking sleep with other activities and goods consumption. The analytical properties are explored showing that there is a total value of sleep time with different components, that equals the value of leisure; that the value of time assigned to any other activity and the value of leisure increase with sleep time if the person sleeps less than medically recommended; and that the way in which sleep time acts on the value of travel time savings varies according to specific behavioral parameters related with the perception of sleep, work and leisure. A system to estimate behavioral and technical parameters econometrically is proposed.
Contributions to Economics, 2004
corresponding author). 1 The hinterland can be defined as that space for which the generalized co... more corresponding author). 1 The hinterland can be defined as that space for which the generalized cost of a port operation is lower than the similar cost using an alternative port. 2 A multiple-purpose (MP) terminal is designed to serve heterogeneous traffic, including non-containerized and containerized cargo. It can be transformed into a specialized one (e.g. containers only) by changing equipment.
The activities time assignment model system: The value of work and leisure for Germans and Chileans
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Papers by Sergio Jara-Diaz