Sequencing Anomalies in Choice Experiments

This paper investigates whether responses to choice experiments (CEs) are subject to sequencing anomalies. While previous research has focussed on the possibility that such anomalies relate to position in the sequence of choice tasks, our research reveals that the particular sequence of tasks matters. Using a novel experimental design that allows us to test our hypotheses using robust nonparametric statistics, we observe sequencing anomalies in CE data similar to those recorded in the dichotomous choice contingent valuation literature. Those sequencing effects operate in both price and commodity dimensions and are observed to compound over a series of choice tasks. Our findings cast serious doubt on the current practice of asking each respondent to undertake several choice tasks in a CE whilst treating each response as an independent observation on that individual’s preferences.Choice experiments; sequencing anomalies; ordering effects; dichotomous choice contingent valuation; non-parametric testing.

Micro-Environment and Plant Assemblage Structure on Virginia\u27s Barrier Island Pimple Dunes

“Pimple” dunes are small, rounded coastal dunes that form along major dune ridges of the barrier islands along the Eastern Shore of Virginia. Although most pimple dunes are small structures ranging between 10 and 20 m in diameter, they have distinct plant assemblages that replicate the upland ecotones of their barrier islands. We examined the relationship between microenvironment, edaphic factors, and plant assemblage structure on pimple dunes. Water availability was an obvious major ecological driver, but we also tested other environmental factors that may correlate with plant assemblage structure. We found distinct assemblage types that segregated themselves by habitat type: marsh, shrub thicket, and dry summit. Freshwater availability was important in delineating vegetation differences, both among transects and among species. However, soil nutrients, such as ammonium, potassium, magnesium, and boron, were also spatially correlated with plant assemblage structure. We hypothesize that interactions between water and other environmental factors (e.g., the accumulation of nutrients in the marsh after they are leached from the dune summits) are important determinants of plant species distribution and abundance, and suggest that more attention be given to micronutrients in future phytosociological studies of barrier islands

ANALIZING WATER FRAMEWORK DIRECTIVE IMPACTS USING A MULTINOMIAL LOGIT LAND USE MODEL

We develop a two-stage, multinomial logit model of UK land use to investigate the impact of policy changes upon agriculture. The model utilizes a large panel database covering the entirety of England and Wales for 14 years between 1969 and 2004 integrated with the economic and physical environment determinants of all major agricultural land use types. Our model performs well in out-of-sample prediction of current land use and we use it to assess a proposed implementation of the Water Framework Directive via a tax on fertilizer. Results indicate that such policy change would generate substantial switching from arable to grassland systems, reducing significantly the amount of nitrate leaching into UK water-bodies.Water Framework Directive, Land use models, Discrete choice models, Multinomial logit, Agricultural and Food Policy, Land Economics/Use, Research Methods/ Statistical Methods, Resource /Energy Economics and Policy,

How clinical and research failures lead to suboptimal prescribing: the example of chronic gout

Despite the existence of several effective drugs for chronic tophaceous gout, management is often neither rational nor effective. Wendy Lipworth and colleagues examine the possible reasons An evidence based or “rational” approach to prescribing is thought to maximise the benefit and minimise the harm from prescription drugs. Unfortunately, prescribing often does not meet this ideal despite clinicians’ best intentions. We use treatment of chronic tophaceous gout to show how apparently irrational prescribing arises from several interacting “failures” in both clinical practice and drug development

Identifying Nonrational Behavior in Recreation Demand Models

In the context of an estimated RPL (Random Parameters Logit) choice model of recreational demand for the game reserves of the KwaZulu-Natal province in South Africa, a test on the existence of an underlying rational preference structure is presented. The proposed procedure allows to identify nonrational behavior in the sample. Using two different data sets extracted from the original data base, we show that by improving the data, apparent nonrationality can be eliminated and welfare analysis may be safely conducted.N/

Coastal wetlands mitigate storm flooding and associated costs in estuaries

As storm-driven coastal flooding increases under climate change, wetlands such as saltmarshes are held as a nature-based solution. Yet evidence supporting wetlands' storm protection role in estuaries—where both waves and upstream surge drive coastal flooding—remains scarce. Here we address this gap using numerical hydrodynamic models within eight contextually diverse estuaries, simulating storms of varying intensity and coupling flood predictions to damage valuation. Saltmarshes reduced flooding across all studied estuaries and particularly for the largest—100 year—storms, for which they mitigated average flood extents by 35% and damages by 37% ($8.4 M). Across all storm scenarios, wetlands delivered mean annual damage savings of$2.7 M per estuary, exceeding annualised values of better studied wetland services such as carbon storage. Spatial decomposition of processes revealed flood mitigation arose from both localised wave attenuation and estuary-scale surge attenuation, with the latter process dominating: mean flood reductions were 17% in the sheltered top third of estuaries, compared to 8% near wave-exposed estuary mouths. Saltmarshes therefore play a generalised role in mitigating storm flooding and associated costs in estuaries via multi-scale processes. Ecosystem service modelling must integrate processes operating across scales or risk grossly underestimating the value of nature-based solutions to the growing threat of storm-driven coastal flooding

Evolution of brown carbon in wildfire plumes

Particulate brown carbon (BrC) in the atmosphere absorbs light at subvisible wavelengths and has poorly constrained but potentially large climate forcing impacts. BrC from biomass burning has virtually unknown lifecycle and atmospheric stability. Here, BrC emitted from intense wildfires was measured in plumes transported over 2 days from two main fires, during the 2013 NASA SEAC4RS mission. Concurrent measurements of organic aerosol (OA) and black carbon (BC) mass concentration, BC coating thickness, absorption Ångström exponent, and OA oxidation state reveal that the initial BrC emitted from the fires was largely unstable. Using back trajectories to estimate the transport time indicates that BrC aerosol light absorption decayed in the plumes with a half-life of 9 to 15 h, measured over day and night. Although most BrC was lost within a day, possibly through chemical loss and/or evaporation, the remaining persistent fraction likely determines the background BrC levels most relevant for climate forcing

Structurally-consistent estimation of use and nonuse values for landscape-wide environmental change

We address the problem of estimating the use and nonuse value derived from a landscape-wide programme of environmental change. Working in the random utility framework, we develop a structural model that describes both demand for recreational trips to the landscape's quality-differentiated natural areas and preferences over different landscape-wide patterns of environmental quality elicited in a choice experiment. The structural coherence of the model ensures that the parameters of the preference function can be simultaneously estimated from the combination of revealed and stated preference data. We explore the properties of the model in a Monte Carlo experiment and then apply it to a study of preferences for changes in the ecological quality of rivers in northern England. This implementation reveals plausible estimates of the use and nonuse parameters of the model and provides insights into the distance decay in those two different forms of value

Urban influence on the concentration and composition of submicron particulate matter in central Amazonia

An understanding of how anthropogenic emissions affect the concentrations and composition of airborne particulate matter (PM) is fundamental to quantifying the influence of human activities on climate and air quality. The central Amazon Basin, especially around the city of Manaus, Brazil, has experienced rapid changes in the past decades due to ongoing urbanization. Herein, changes in the concentration and composition of submicron PM due to pollution downwind of the Manaus metropolitan region are reported as part of the GoAmazon2014/5 experiment. A high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) and a suite of other gas- and particle-phase instruments were deployed at the T3 research site, 70&thinsp;km downwind of Manaus, during the wet season. At this site, organic components represented 79&plusmn;7&thinsp;% of the non-refractory PM1 mass concentration on average, which was in the same range as several upwind sites. However, the organic PM1 was considerably more oxidized at T3 compared to upwind measurements. Positive-matrix factorization (PMF) was applied to the time series of organic mass spectra collected at the T3 site, yielding three factors representing secondary processes (73&plusmn;15&thinsp;% of total organic mass concentration) and three factors representing primary anthropogenic emissions (27&plusmn;15&thinsp;%). Fuzzy c-means clustering (FCM) was applied to the afternoon time series of concentrations of NOy, ozone, total particle number, black carbon, and sulfate. Four clusters were identified and characterized by distinct air mass origins and particle compositions. Two clusters, Bkgd-1 and Bkgd-2, were associated with background conditions. Bkgd-1 appeared to represent near-field atmospheric PM production and oxidation of a day or less. Bkgd-2 appeared to represent material transported and oxidized for two or more days, often with out-of-basin contributions. Two other clusters, Pol-1 and Pol-2, represented the Manaus influence, one apparently associated with the northern region of Manaus and the other with the southern region of the city. A composite of the PMF and FCM analyses provided insights into the anthropogenic effects on PM concentration and composition. The increase in mass concentration of submicron PM ranged from 25&thinsp;% to 200&thinsp;% under polluted compared with background conditions, including contributions from both primary and secondary PM. Furthermore, a comparison of PMF factor loadings for different clusters suggested a shift in the pathways of PM production under polluted conditions. Nitrogen oxides may have played a critical role in these shifts. Increased concentrations of nitrogen oxides can shift pathways of PM production from HO2-dominant to NO-dominant as well as increase the concentrations of oxidants in the atmosphere. Consequently, the oxidation of biogenic and anthropogenic precursor gases as well as the oxidative processing of preexisting atmospheric PM can be accelerated. This combined set of results demonstrates the susceptibility of atmospheric chemistry, air quality, and associated climate forcing to anthropogenic perturbations over tropical forests.</p