Discrete choice modelling incorporating attribute thresholds of perception

In this paper we formulate a discrete choice model that incorporates thresholds in the perception of attribute changes. The model considers multiple options and allows changes in several attributes. We postulate that if thresholds exist they could be random, differ between individuals, and even be a function of socio-economic characteristics and choice conditions. Our formulation allows estimation of the parameters of the threshold probability distribution starting from information about choices. The model is applied to synthetic data and also to real data from a stated preference survey. We found that where perception thresholds exist in the population, the use of models without them leads to errors in estimation and prediction. Clearly, the effect is more relevant when the typical size of change in the attribute value is comparable with the threshold, and when the contribution of this attribute in the utility function is substantial. Finally, we discuss the implications of the threshold model for estimation of the benefits of transport investments, and show that where thresholds exist, models that do not represent them can overestimate benefits substantially

Inertia and shock effects on mode choice panel data: implications of the Transantiago implementation

The mode choice process, especially in the case of commuter trips, reflects the strong tendency people have to simplify the assessment of their options when confronted with successive well-known decisions. Thus, it is common to repeat the “habitual” choice over time involving a potentially important inertia element. However, while inertia effects increase the probability of maintaining the same choice in a stable situation, in a changing environment i.e. one that is disrupted by a radical or significant policy intervention, user behaviour may be affected by a specific response to abrupt changes. Shock effects of this kind could increase the probability of individuals leaving their habitual choices. Temporal effects have been commonly ignored in practical studies, as most demand models to date have been based on cross-sectional data. A few recent studies dealing with panel data have managed to incorporate inertia effects, but there are no studies that have included both inertia and shock effects. To address this, we started by building a data panel around the introduction of a new and radical policy for the conurbation of Santiago de Chile. The final aim was to develop mode choice models incorporating the effects of three main forces involved in the choice process: (1) the relative values of the modal attributes, (2) the inertia effect, and (3) the shock resulting from and abrupt policy intervention. This paper presents the formulation of an inertia-shock model and its application to each of simulated and real data. The results confirm that changing systems should be modelled respecting the presence of both inertia and shock effects, otherwise serious errors in model estimation may arise

Treatment of reference alternatives in stated choice surveys for air travel choice behaviour

Stated Choice (SC) surveys are increasingly being used instead of Revealed Preference (RP) surveys for the study of air travel choice behaviour. In many cases, the choice situations presented in these SC surveys are constructed around an observed trip, where this is often included as one of the alternatives. Classically, these RP alternatives have been treated in the same way as the SC alternatives. The applications presented in this paper show that this potentially leads to biased results, and that it is important to recognise the differences in the nature of the two types of alternative. Additionally, the paper discusses issues caused by respondents who consistently prefer the RP alternative over the SC alternatives, a common phenomenon in such SC data

The Place of Sense Perception in Thirteenth-Century Encyclopaedias

Several studies have approached sense perception in the encyclopaedias of Thomas of Cantimpré, Bartholomew the Englishman and Vincent of Beauvais. Yet a systematic overview and comparison of the arrangement of sense perception in these encyclopaedias is still lacking. The overview offered here shows that all encyclopaedias place sense perception beside expositions on psychology and anatomy. There are, however, significant differences in how they treat the objects of sensation. In the case of Bartholomew and Vincent, I argue, these differences reflect two different readings of Aristotle

Some consistent finite element formulations of 1-D beam models: a comparative study

A consistent Finite Element formulation was developed for four classical 1-D beam models. This formulation is based upon the solution of the homogeneous differential equation (or equations) associated with each model. Results such as the shape functions, stiffness matrices and consistent force vectors for the constant section beam were found. Some of these results were compared with the corresponding ones obtained by the standard Finite Element Method (i.e. using polynomial expansions for the field variables). Some of the difficulties reported in the literature concerning some of these models may be avoided by this technique and some numerical sensitivity analysis on this subject are presented

Asymmetric preference formation in willingness to pay estimates in discrete choice models

Individuals when faced with choices amongst a number of alternatives often adopt a variety of processing rules, ranging from simple linear to complex non-linear treatment of each attribute defining the offer of each alternative. In this paper we investigate the presence of asymmetry in preferences to test for reference effects and differential willingness to pay according to whether we are valuing gains or losses. The findings offer clear evidence of an asymmetrical response to increases and decreases in attributes when compared to the corresponding values for a reference alternative, where the degree of asymmetry varies across attributes and population segments

Prevalencia de anticuerpos anti-toxoplasma gondii.

68 p.La toxoplasmosis es una de las zoonosis parasitarias de gran relevancia para el hombre, su importancia radica en los efectos que produce en mujeres embarazadas y pacientes inmunocomprometidos, siendo agente causal de encefalitis, miocarditis, neumonitis y hepatitis y malformaciones en periodo de gestación. Si bien es muy baja la frecuencia de casos clínicos, se estima que existe una alta prevalencia de ésta mayormente ligada a cuadros de carácter subclínico. En esta revisión, se intentó resumir las tendencias de seroprevalencia de Toxoplasma gondii en Latinoamérica, a través de numerosos estudios segregados para determinadas áreas, si bien algunos ofrecen información extendida del país en estudio, siendo representativas y confiables; en otros países la información disponible es limitada ya que solo existen estudios para ciertas regiones, la muestra utilizada no es representativa del país, por lo cual es solo aplicable al tipo de población estudiada. Dentro de la literatura, se observó que la mayoría de los países de América Latina muestran significativamente altas tasas de seropositividad, con excepción de un estudio de la población general nacional en Chile y México. Comparándose con regiones de África, que también tuvieron altas tasas de prevalencia e incluso los factores de riesgos fueron similares. Se contrastaron dichas tasas en países desarrollados, los cuales presentan una baja prevalencia para Toxoplasma como es el caso de Estados Unidos y Europa

Adolescent Bullying Victimization and Life Satisfaction: Can Family and School Adult Support Figures Mitigate this Effect?

Indexación: Scopus.Existen pocos estudios que vinculen la victimización sufrida por bullying con la satisfacción con la vida. Por ello, este estudio tiene como objetivo evaluar el efecto mitigador del apoyo de figuras adultas (padres, madres y adultos de la escuela) sobre la relación de la victimización por bullying y la satisfacción con la vida en adolescentes. Con este fin, se evalúa una muestra de 5774 adolescentes provenientes de 71 escuelas públicas ubicadas en barrios violentos de Lima, Perú. Para ello, se realiza un análisis de moderación para evaluar el rol de las figuras adultas de apoyo en la casa y la escuela. Los resultados muestran que el apoyo de los adultos en casa mitiga la relación negativa entre la victimización y la satisfacción con la vida. Este efecto es mayor en el caso del apoyo adulto en la casa. El apoyo brindado por los adultos, tanto en la casa como en la escuela, favorece que los adolescentes que padecen de una alta prevalencia de victimización puedan mantener niveles superiores de satisfacción con la vida respecto a los adolescentes que perciben bajo apoyo de los adultos. Finalmente, se discute la necesidad de que adultos en la escuela y padres realicen acciones coordinadas para prevenir y disminuir la prevalencia de este tipo de violencia entre compañeros/as.There are still few studies relating bullying victimization and life satisfaction. This study aimed to assess the mitigating effect of adult figures support (at school and home) on the relationship between bullying victimization and life satisfaction experienced by adolescents. To this end, a sample of 5774 adolescents from 71 public schools located throughout the violent neighborhoods of Lima (Perú) was evaluated. A moderation analysis was performed to assess the moderating role of support adult figures from home and school. The results show that the support of adults at home and school mitigate the negative effect of bullying victimization on life satisfaction, and this effect is larger in the case of adult home support. Adult support at home and school help students with high prevalence of bullying victimization maintain high levels of life satisfaction compared to adolescents with low support from adults. Finally, the need for adults at school and home to take joint measures to prevent and reduce the prevalence of this type of peer violence is discussed.https://www.sciencedirect.com/science/article/pii/S1136103417302332?via%3Dihu