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.

On the relationships between auditory and visual factors in a residential environment context: A SEM approach.

To understand the effects of specific elements that may enhance or detract residents' well-being, it is important to explore the relationships between auditory and visual factors, based on people's sensory experiences. Although residential environments provide natural experimental conditions to observe these relationships, the complexity of measuring sensory perceptions and their subsequent interpretation constitutes a challenge. This study aims to identify the influence of socio-demographics and residential location characteristics on three latent variables: noise-Sensitivity, sound-Pleasantness, and visual-Liveability in a Latin American city. The methodology is replicable and relies on a digital survey that displays environments in 360-format video and uses sound immersion techniques; it was applied to a sample of household heads in Quito, Ecuador. Based on an efficient experimental design, we selected different residential environments according to acoustic-visual attributes and the proximity to residential, commercial, and recreational land uses. Structural Equation Models (SEM) were estimated using mediating variables. Our results reveal the influence of noise-Sensitivity on sound-Pleasantness and, indirectly, on visual-Liveability. Further analysis shows that the impact of sound and visual perception changes with different socio-demographics and residential location characteristics.

Characterising public transport shifting to active and private modes in South American capitals during the COVID-19 pandemic.

During the year 2020, the COVID-19 pandemic affected mobility around the world, significantly reducing the number of trips by public transport. In this paper, we study its impact in five South American capitals (i.e., Bogotá, Buenos Aires, Lima, Quito and Santiago). A decline in public transport patronage could be very bad news for these cities in the long term, particularly if users change to less sustainable modes, such as cars or motorbikes. Notwithstanding, it could be even beneficial if users selected more sustainable modes, such as active transport (e.g., bicycles and walking). To better understand this phenomenon in the short term, we conducted surveys in these five cities looking for the main explanation for changes from public transport to active and private modes in terms of user perceptions, activity patterns and sociodemographic information. To forecast people's mode shifts in each city, we integrated both objective and subjective information collected in this study using a SEM-MIMIC model. We found five latent variables (i.e., COVID-19 impact, Entities response, Health risk, Life related activities comfort and Subjective well-being), two COVID-19 related attributes (i.e., new cases and deaths), two trip attributes (i.e., cost savings and time), and six socio-demographic attributes (i.e., age, civil status, household characteristics, income level, occupation and gender) influencing the shift from public transport to other modes. Furthermore, both the number of cases and the number of deaths caused by COVID-19 increased the probability of moving from public transport to other modes but, in general, we found a smaller probability of moving to active modes than to private modes. The paper proposes a novel way for understanding geographical and contextual similarities in the pandemic scenario for these metropolises from a transportation perspective.

The path towards herd immunity: Predicting COVID-19 vaccination uptake through results from a stated choice study across six continents.

Despite unprecedented progress in developing COVID-19 vaccines, global vaccination levels needed to reach herd immunity remain a distant target, while new variants keep emerging. Obtaining near universal vaccine uptake relies on understanding and addressing vaccine resistance. Simple questions about vaccine acceptance however ignore that the vaccines being offered vary across countries and even population subgroups, and differ in terms of efficacy and side effects. By using advanced discrete choice models estimated on stated choice data collected in 18 countries/territories across six continents, we show a substantial influence of vaccine characteristics. Uptake increases if more efficacious vaccines (95% vs 60%) are offered (mean across study areas = 3.9%, range of 0.6%-8.1%) or if vaccines offer at least 12 months of protection (mean across study areas = 2.4%, range of 0.2%-5.8%), while an increase in severe side effects (from 0.001% to 0.01%) leads to reduced uptake (mean = -1.3%, range of -0.2% to -3.9%). Additionally, a large share of individuals (mean = 55.2%, range of 28%-75.8%) would delay vaccination by 3 months to obtain a more efficacious (95% vs 60%) vaccine, where this increases further if the low efficacy vaccine has a higher risk (0.01% instead of 0.001%) of severe side effects (mean = 65.9%, range of 41.4%-86.5%). Our work highlights that careful consideration of which vaccines to offer can be beneficial. In support of this, we provide an interactive tool to predict uptake in a country as a function of the vaccines being deployed, and also depending on the levels of infectiousness and severity of circulating variants of COVID-19.

A systematic review and meta-analysis of the efficacy of processing stages and interventions for controlling Campylobacter contamination during broiler chicken processing.

Systematic review and meta-analysis were conducted to quantify the effects of processing stages and interventions on the prevalence and concentration of Campylobacter on broiler carcasses. To comprehensively capture relevant evidence, six databases were searched using the keywords "Campylobacter" and "broiler chicken." The literature search yielded 10,450 unique citations, and after applying predetermined inclusion and exclusion criteria, 72 and 53 relevant citations were included in meta-analyses for processing stages and interventions, respectively. As the two primary outcomes, log reduction and prevalence changes were estimated for each stage or intervention using a random-effects meta-analysis approach whenever possible. The outcome-level quality assessment was conducted following the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. The analysis revealed that scalding and chilling majorly reduces the prevalence and concentration of Campylobacter. Immersion chilling reduces the concentration regardless of chemical additives, but its effect on prevalence is not conclusive. The effects of carcass washing applications remain uncertain due to the inconsistency and imprecision of both outcomes. Defeathering and evisceration were identified as stages that can increase both prevalence and concentration. Both chemical and physical processing interventions provide limited efficacy in concentration and prevalence reduction. Major limitations of the review were inconsistency and imprecision at the outcome level and reporting issues and data gaps at the study level. The results are expected to inform quantitative microbial risk assessment model development and support evidence-based decision-making.

Capturing and analysing heterogeneity in residential greywater reuse preferences using a latent class model.

To legally permit greywater reuse as a management strategy, it is necessary to establish allowed uses, as well as guarantee legitimacy, safety and maintain public trust. Cities with previous experience in greywater reuse have reconfigured their regulations according to their own evidence with decentralized water reuse systems. This has allowed them to encourage or restrict certain indoor uses of treated greywater. However, cities starting to use these residential schemes lack the experience to reconfigure their water and sanitation regulation, and thus need "blindly" decide on the type of greywater uses to allow in order to achieve a balance between users' acceptability and avoiding public health problems. In this research, we analyse hypothetical situations of greywater reuse based on real evidence related to decentralized water systems. The main objective of this study is to evaluate the heterogeneity of individuals' preferences regarding residential greywater reuse for six intended indoor uses, using stated choice experiments and a latent class model. Hence, we obtain preliminary evidence about the direction that the regulation or pilot tests should take. We use the context of Santiago (Chile) as a reference, where although allowed, greywater reuse is not taking place widely. Our results show that survey respondents can be classified into four classes (enthusiasts, greywater sceptics, appearance conscious and water expenditure conscious), according to the preferences for the different types of indoor greywater reuse and the appearance of the treated greywater. From a policy perspective, our results show differences across classes as a function of socioeconomic characteristics and previous greywater reuse knowledge, as well as wider household characteristics, including the presence of sensitive individuals (under 15 and over 74 years old), number of residents, number of sanitary devices, and location and type of garden.

Understanding the preferences for different types of urban greywater uses and the impact of qualitative attributes.

Greywater reuse can allow substantial improvements in the efficiency of potable water systems. However, widespread uptake of greywater reuse depends on its acceptability by the population. Previous studies have assessed the implementation costs of greywater reuse technology, and considered its acceptability in principle. Although cost is clearly very important in terms of adopting/installing the technology, the actual perception of greywater reuse is crucial in driving the acceptability of use and the long-term success of the technology. This study uses discrete choice models to quantify, for the first time, the preferences of different socio-economic groups for greywater of different quality (colour, odour) and for different uses inside homes. A stated choice survey that removed the influence of installation costs was developed, and implemented in Santiago, Chile. Although legislation allows greywater use in Santiago, it does not take place at any meaningful scale. Results show that, in decreasing order of preference, there is an overall acceptance for using high quality treated greywater for toilet flushing, laundry, garden irrigation, hand washing and, shower/bathtub use, but not for drinking. When the quality of appearance in terms of colour and odour gets worse, monetary incentives could be needed even for those uses that do not involve human contact. Gender, age, educational level, water expenditure level, and in particular previous knowledge about greywater reuse, are important determinants of acceptability and thus willingness to pay for greywater use; however, their importance varies according to the type of use. Our results provide important insights for understanding the conditions that would precipitate rapid and wide uptake of greywater reuse in cities, and thereby make better use of limited water resources.

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.

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.

Willingness-to-pay for reducing fatal accident risk in urban areas: an Internet-based Web page stated preference survey.

Contemporary transport project evaluation requires the ability to value reductions in the number of estimated fatal and non-fatal accidents after project implementation. In this quest, we designed a stated preference (SP) experiment to estimate willingness-to-pay (WTP) for reducing fatal accident risk in urban areas. The survey was implemented in a Web page allowing rapid turnover and a complete customisation of the interview. The sample was presented with a series of route choice situations based on travel time, cost and number of car fatal accidents per year. With this data we estimated Multinomial Logit (MNL) and Mixed Logit (ML) models based on a consistent microeconomic framework; the former with linear and non-linear utility specifications and allowing for various stratifications of the data. The more flexible ML models also allow to treat the repeated observations problem common to SP data and, as expected, gave a better fit to the data in all cases. Based on these models, we estimated subjective values of time, that were consistent with previous values obtained in the country, and also sensible values for the WTP for reductions in fatal accident risk. Thus, the Internet appears as a potentially very interesting medium to carry out complex stated choice surveys.

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.

Fracturas pertrocantereas: osteosíntesis con tornillo deslizante de Richards / Trocantheric fractures: osteosynthesis DHS device

Se efectuó estudio prospectivo en 139 pacientes operados de fracturas pertrocantéreas de fémur en el Hospital Militar de Santiago, que fueron intervenidos entre enero de 1984 y diciembre de 1989 y fueron seguidos durante un año. La casuística está formada por 22 hombres (15,83 por ciento) y 117 mujeres 84,17 por ciento con un promedio de edad de 77,4 años. Se usó la clasificación de Massie-Evans siendo 48,2 por ciento estables y 51,8 por ciento inestables. Se analiza el tratamiento efectuado: A) Osteosíntesis DHS con reducción anatómica en 74,8 por ciento y B) Osteosíntesis DHS con osteotomia de Dimon Hughston en 25,8 por ciento. Los resultados clínicos se evaluaron según la escala de Harris, obteniéndose un 56,14 por ciento buenos, 38,6 por ciento regular y 5,26 por ciento malos Hubo. 5,76 por ciento complicaciones generales y 8,63 por ciento por defectos de técnica