A meta-analysis of wage-risk estimates of the value of a statistical life

This paper presents the results of a meta-analysis of estimates of the value of statistical life (VOSL). Data on the sample characteristics, data sources and analytical approach used to derive some 60 separate estimates in 17 published papers are used in the analysis. Tests lead us to reject the hypothesis that this sample shows evidence of publication bias. A meta-regression of these estimates provides evidence that VOSL is increasing in income but is invariant with respect to baseline risk. Controlling for aspects of the sample, data sources and analytical approach allows us to derive a best estimate of the VOSL of around $7 million

Do scenario context and question order influence WTP? The application of a model of uncertain WTP to the CV of the morbidity impacts of air pollution

This paper presents a general framework for modelling responses to contingent valuation questions when respondents are uncertain about their ‘true’ WTP. These models are applied to a contingent valuation data set recording respondents’ WTP to avoid episodes of ill-health. Two issues are addressed. First, whether the order in which a respondent answers a series of contingent valuation questions influences their WTP. Second, whether the context in which a good is valued (in this case the information the respondent is given concerning the cause of the ill-health episode or the policy put into place to avoid that episode) influences respondents’ WTP. The results of the modelling exercise suggest that neither valuation order nor the context included in the valuation scenario impact on the precision with which respondents answer the contingent valuation questions. Similarly, valuation order does not appear to influence the mean or median WTP of the sample. In contrast, it is shown that in some cases, the inclusion of richer context significantly shifts both the mean and median WTP of the sample. This result has implications for the application of benefits transfer. Since, WTP to avoid an episode of ill-health cannot be shown to be independent of the context in which it is valued, the validity of transferring benefits of avoided ill-health episodes from one policy context to another must be called into question

A recreational demand model of wildlife-viewing visits to the game reserves of the Kwazulu-Natal province of South Africa

In recent years, random utility models (RUMs) have become an increasingly popular approach to estimating the welfare benefits derived by visitors to recreational sites. Researchers using such models have tended to concentrate on the choice between sites; explaining a visitor’s decision by means of the different qualities of the available sites and the different costs of travelling to those sites. This is all well and good for ‘day trips’ but for recreational trips characterised by visits lasting a number of days, concentrating solely on the choice between sites may be a gross oversimplification. For such ‘away-breaks’, a visitor’s choice of accommodation and length of stay may be just as important as the qualities of the site and the length of the journey in determining the costs and benefits that result from the trip. This paper describes the application of a RUM known as a nested multinomial logit model (NMNL), which distinguishes the three dimensions of choice that characterise away-breaks; duration of stay, choice of recreational site and choice of accommodation type. Four costs are important in determining choice for such trips; the cost of travel to the recreational site, the cost of accommodation at the site, the cost of time whilst travelling and the cost of time whilst on-site. Previous applications have frequently assumed that travel time can be valued at some exogenously determined proportion of the wage rate, whilst at the same time ignoring the value of time spent on site. The specification of the indirect utility function in the model presented here, allows for the value of time to be inferred from the data by estimating the proportion of the wage rate that most appropriately values a unit of time spent in different activities. The model is applied to a unique dataset that records details of trips made by domestic households to the game reserves of the KwaZulu-Natal province of South Africa. These trips are typical of away-breaks, since visitors tend to travel fairly large distances to visit the reserves and typically stay one or more nights on site. Each of the game reserves affords visitors different wildlife-viewing opportunities and provides a variety of accommodation facilities that vary greatly in their quality and price. Geographical information system (GIS) techniques have been used to establish exact door to gate distances and provide accurate estimates of travel costs and travel times that take account of assumed road speeds. GIS techniques have also been employed to garner socio-economic data on the households in the dataset. One further novel feature of the data is the use of complex computer algorithms to accurately establish the choice sets faced by individual households. The three-level NMNL model is estimated using a full information maximum likelihood (FIML). The results of the analysis support the work of De Serpa (1971) in that they suggest that recreationists have a positive willingness to pay to save time in travelling to a reserve, but as would be expected, are not willing to pay anything to save time spent on site. The model is used to calculate welfare estimates for continued access to the different game reserves. Average per-trip estimates of the consumer surplus enjoyed by domestic visitors range from around $15 for one reserve, up to almost$50 for another. Boot-strapping techniques have been employed to calculate standard errors for these benefit estimates

Computational Nuclear Physics and Post Hartree-Fock Methods

We present a computational approach to infinite nuclear matter employing Hartree-Fock theory, many-body perturbation theory and coupled cluster theory. These lectures are closely linked with those of chapters 9, 10 and 11 and serve as input for the correlation functions employed in Monte Carlo calculations in chapter 9, the in-medium similarity renormalization group theory of dense fermionic systems of chapter 10 and the Green's function approach in chapter 11. We provide extensive code examples and benchmark calculations, allowing thereby an eventual reader to start writing her/his own codes. We start with an object-oriented serial code and end with discussions on strategies for porting the code to present and planned high-performance computing facilities.Comment: 82 pages, to appear in Lecture Notes in Physics (Springer), "An advanced course in computational nuclear physics: Bridging the scales from quarks to neutron stars", M. Hjorth-Jensen, M. P. Lombardo, U. van Kolck, Editor

Organic nitrate aerosol formation via NO³ + biogenic volatile organic compounds in the southeastern United States

Gas- and aerosol-phase measurements of oxidants, biogenic volatile organic compounds (BVOCs) and organic nitrates made during the Southern Oxidant and Aerosol Study (SOAS campaign, Summer 2013) in central Alabama show that a nitrate radical (NO₃) reaction with monoterpenes leads to significant secondary aerosol formation. Cumulative losses of NO₃ to terpenes are correlated with increase in gasand aerosol-organic nitrate concentrations made during the campaign. Correlation of NO₃ radical consumption to organic nitrate aerosol formation as measured by aerosol mass spectrometry and thermal dissociation laser-induced fluorescence suggests a molar yield of aerosol-phase monoterpene nitrates of 23–44 %. Compounds observed via chemical ionization mass spectrometry (CIMS) are correlated to predicted nitrate loss to BVOCs and show C₁₀H₁₇NO₅, likely a hydroperoxy nitrate, is a major nitrate-oxidized terpene product being incorporated into aerosols. The comparable isoprene product C₅H₉NO₅ was observed to contribute less than 1% of the total organic nitrate in the aerosol phase and correlations show that it is principally a gas-phase product from nitrate oxidation of isoprene. Organic nitrates comprise between 30 and 45% of the NOy budget during SOAS. Inorganic nitrates were also monitored and showed that during incidents of increased coarse-mode mineral dust, HNO₃ uptake produced nitrate aerosol mass loading at a rate comparable to that of organic nitrate produced via NO₃ CBVOCs

A simplified (modified) Duke Activity Status Index (M-DASI) to characterise functional capacity: A secondary analysis of the Measurement of Exercise Tolerance before Surgery (METS) study

Background Accurate assessment of functional capacity, a predictor of postoperative morbidity and mortality, is essential to improving surgical planning and outcomes. We assessed if all 12 items of the Duke Activity Status Index (DASI) were equally important in reflecting exercise capacity. Methods In this secondary cross-sectional analysis of the international, multicentre Measurement of Exercise Tolerance before Surgery (METS) study, we assessed cardiopulmonary exercise testing and DASI data from 1455 participants. Multivariable regression analyses were used to revise the DASI model in predicting an anaerobic threshold (AT) >11 ml kg −1 min −1 and peak oxygen consumption (VO 2 peak) >16 ml kg −1 min −1, cut-points that represent a reduced risk of postoperative complications. Results Five questions were identified to have dominance in predicting AT>11 ml kg −1 min −1 and VO 2 peak>16 ml.kg −1min −1. These items were included in the M-DASI-5Q and retained utility in predicting AT>11 ml.kg −1.min −1 (area under the receiver-operating-characteristic [AUROC]-AT: M-DASI-5Q=0.67 vs original 12-question DASI=0.66) and VO 2 peak (AUROC-VO2 peak: M-DASI-5Q 0.73 vs original 12-question DASI 0.71). Conversely, in a sensitivity analysis we removed one potentially sensitive question related to the ability to have sexual relations, and the ability of the remaining four questions (M-DASI-4Q) to predict an adequate functional threshold remained no worse than the original 12-question DASI model. Adding a dynamic component to the M-DASI-4Q by assessing the chronotropic response to exercise improved its ability to discriminate between those with VO 2 peak>16 ml.kg −1.min −1 and VO 2 peak<16 ml.kg −1.min −1. Conclusions The M-DASI provides a simple screening tool for further preoperative evaluation, including with cardiopulmonary exercise testing, to guide perioperative management

Associations of autozygosity with a broad range of human phenotypes

In many species, the offspring of related parents suffer reduced reproductive success, a phenomenon known as inbreeding depression. In humans, the importance of this effect has remained unclear, partly because reproduction between close relatives is both rare and frequently associated with confounding social factors. Here, using genomic inbreeding coefficients (F-ROH) for >1.4 million individuals, we show that F-ROH is significantly associated (p <0.0005) with apparently deleterious changes in 32 out of 100 traits analysed. These changes are associated with runs of homozygosity (ROH), but not with common variant homozygosity, suggesting that genetic variants associated with inbreeding depression are predominantly rare. The effect on fertility is striking: F-ROH equivalent to the offspring of first cousins is associated with a 55% decrease [95% CI 44-66%] in the odds of having children. Finally, the effects of F-ROH are confirmed within full-sibling pairs, where the variation in F-ROH is independent of all environmental confounding.Peer reviewe