Influence of survey engagement and multiple-choice heuristics in the estimation of the value of a statistical life.

Estimating the value of non-market goods, such as reductions in mortality risks due to traffic accidents or air pollution, is typically done using stated choice (SC) data. However, issues with potential estimation biases due to the hypothetical nature of SC experiments arise, as protest choices are common and survey engagement is not constant across respondents. Further, if respondents choose to use different choice mechanisms and this is not considered, the results may also be biased. We designed an SC experiment to estimate the willingness to pay (WTP) for mortality risk reductions, that allowed us to simultaneously estimate the WTP to reduce the risk of traffic accident deaths and cardiorespiratory deaths due to air pollution. We formulated and estimated a multiple heuristic latent class model that also considered two latent constructs: Institutional Belief, to consider protest responses, and survey Engagement as a class membership covariate. We found, first, that individuals with lower institutional belief gave a higher probability of choice to the status-quo alternative, shying away from programs involving governmental action. Second, that not identifying respondents who do not appropriately engage in the experiment, biased the WTP estimators. In our case WTP decreased up to 26% when two different choice heuristics were allowed for in the model.

Exploring the role of delta-V in influencing occupant injury severities - A mediation analysis approach to motor vehicle collisions.

This study investigates the impact that delta-V, the relative change in vehicle velocity pre- and post-crash, has on the severity of motor vehicle collisions (MVCs). We study injury severity using two metrics for each occupant - the number of injuries suffered, and the probability of suffering a serious or worse (MAIS 3+) injury. We use a cross-sectional set of generally-representative MVC data between 2010 and 2015 as a basis for our research. Collision factors that influence the crash environment are combined with the injuries that were suffered in MVCs. The influence of delta-V is captured using a mediation analysis, whereby delta-V acts as the focal point between crash factors and injury outcome. The mediation approach adds to existing research by presenting a detailed view of the relationship between injury severity, delta-V and other collision factors. We find evidence of competitive mediation, wherein a collision factor's positive association with injury severity is offset by a negative association with delta-V. Neglecting to include delta-V in our study would have let the factor's association with injury severity go undiscovered. In addition, certain collision factors are found to be related to injury severity solely because of delta-V, while others are found to have a significant impact regardless of delta-V. Our results support the multitude of policy recommendations that promote seatbelt use and warn against alcohol-impaired driving, and support the proliferation of safety-enabled vehicles whose technology can mitigate the bodily damage associated with detrimental crash types.

A comparison of bus passengers' and car drivers' valuation of casualty risk reductions in their routes.

INTRODUCTION: The economic value of safety represents an important guide to transport policy, and more studies on individuals' valuation of road safety are called for. This paper presents a stated preference study of the value of preventing fatal and serious injuries involving bus passengers and car drivers in road accidents. OBJECTIVES: Former valuation studies based on travel behaviour and route choice have involved primarily car drivers. Our study also included bus passengers, thus providing a comparison of two types of transport mode users. Moreover, the comparison was based on two different valuation methods. METHODOLOGY: About 600 bus passengers and nearly 2300 car users from different areas of Norway reported a recent trip, described by its distance and travel cost. Then they answered stated choice tasks that took a reference in the reported trip and involved trade-offs among travel time, fatal and seriously injured victims and travel costs. Afterwards, they faced a simple trade-off between travel costs, and fatal and seriously injured victims. FINDINGS: Pooling the data from the two stated preference formats, we derived values of a statistical life and of a statistical seriously injured victim. Regarding the value of statistical life, our point estimates were NOK 45.5 million and NOK 58.3 million for bus users and car users respectively. DISCUSSION: The point estimates for bus passengers and car users were not statistically different given their confidence intervals. Thus, we recommend the use of a single value, identical for both modes of transport, for the prevention of a statistical fatality as well as for a statistical injury.

Valuing air quality impacts using stated choice analysis: trading off visibility against morbidity effects.

Direct valuation of air quality has as a drawback; that estimated willingness to pay figures cannot be apportioned to the several environmental goods affected by air quality, such as mortality and morbidity effects, visibility, outdoor recreation, among others. To address this issue, we implemented a survey in Santiago de Chile to identify component values of confounded environmental services by means of a choice experiment. We designed a survey where two environmental goods, a morbidity health endpoint and improved visibility, had to be jointly traded off against each other and against money in a unified framework. The health endpoint is a respiratory illness that results in an emergency room visit with a probability of hospitalization being required for appropriate treatment. Visibility is described as an aesthetic effect related to the number of days per year of high visibility. Modeling comprises both a logit model with covariates and a mixed-logit model. The results suggest that the health endpoint midpoint value is in a range from USD 2,800 to USD 13,000, mainly depending on the model and age stratum. The mid point value of an extra day of high visibility per year ranges from USD 281,000 to USD 379,000.

On the joint valuation of averting fatal and severe injuries in highway accidents.

INTRODUCTION: To evaluate the benefits of road transport safety projects, planners need the monetary value of averting fatal and severe injuries. Usually, contingent valuation and risk-risk studies have been used. The contexts posed by both survey techniques do not represent the choice situation a driver faces when having to choose among alternative routes with different levels of safety. METHOD: We set up a stated choice web page survey in which individuals had to choose between two routes for a hypothetical trip between two cities; thus implicitly revealing their preferences for safety both in terms of reducing the number of fatal victims and of severely injured victims. RESULTS: For Chilean routes we were able to estimate approximate values of US$300,000 and US$140,000 for a reduction in one fatality and one severely injured victim, respectively. IMPACTS: Our evidence could be valuable for road planners in other developing nations.

Stated preference in the valuation of interurban road safety.

In Chile, as in most less-developed nations, if life savings are valued at all the human capital approach is used in a rather non-consistent fashion. As part of a 5-year research project on the value of transport externalities, a stated preference (SP) experiment was carried out in order to assess the value of a statistical life for Chilean interurban motorways. Interviewees had to choose among different routes for a hypothetical trip, based on the following attributes: travel time, toll charge and level of risk. The results of our experiment show that people were sensitive to the risk variable, thus "stating" a preference for safer routes. Several models were estimated with linear and non-linear utility specifications, and also incorporating the effects of socio-economic variables in a novel and interesting fashion. We were able to estimate subjective values of time consistent with previous values obtained in the country and reasonably looking values (in comparison to Chilean prices and foreign experience) of a statistical life. The paper discusses the experimental design, data collection and analysis, with emphasis on the role of lexicographic individuals that are a feature of SP studies that has not been carefully explored in the literature. We also present our modelling results and compare our derived values (of time and of a statistical life) with values found previously and/or elsewhere.

Amlodipino en hipertensión arterial en el centro médico naval "CMST" / Amlodipine in hypertension at the Naval Medical Center

Objetivo. Comprobar la eficacia y tolerabilidad del amlodipino en el tratamiento de la hipertensión arterial (HTA) en pacientes de sexo masculino y femenino atendidos en el consultorio de Cardiología del Centro Médico Naval "CMST' del Perú. Participantes y Métodos. Se estudió el efecto deamlodipino en 20 pacientes mayores de 18 años portadores de HTA. Resultados. Al cabo de 8 semanas de tratamientocon amlodipino el 94'70 de pacientes normalizó su presión arterial, con una disminución mayor de 9mmHg en la presión arterial diastólica y excelentetolerancia por la ausencia de efectos secundarios significativos.Conclusiones. El amlodipino utilizado en el presente estudio fue eficaz y seguro en el tratamiento de la HTA esencial estadío I-II, en dosis única de 5 a 10mg. por día, y puede ser utilizado como agente único para controlar la hipertensión.