Modelling distributed lag effects in epidemiological time series studies

The paper argues that much of the existing literature on air pollution and mortality deals only with the transient effects of air pollution. Policy, on the other hand, needs to know when, whether and to what extent pollution-induced increases in mortality are reversed. This involves modelling the entire distributed lag effects of air pollution. Borrowing from econometrics this paper presents a method by which distributed lag effects can be estimated parsimoniously but plausibly estimated. The paper presents a time series study into the relationship between ambient levels of air pollution and daily mortality counts for Manchester employing this technique. Black Smoke is shown to have a highly significant effect on mortality counts in the short term. Nevertheless we find that 80 percent of the deaths attributable to BS would have occurred anyway within one week whereas the remaining 20 percent of individuals would otherwise have enjoyed a normal life expectancy

Phase transition in the globalization of trade

Globalization processes interweave economic structures at a worldwide scale, trade playing a central role as one of the elemental channels of interaction among countries. Despite the significance of such phenomena, measuring economic globalization still remains an open problem. More quantitative treatments could improve the understanding of globalization at the same time that help a formal basis for comparative economic history. In this letter, we investigate the time evolution of the statistical properties of bilateral trade imbalances between countries in the trade system. We measure their cumulative probability distribution at different moments in time to discover a sudden transition circa 1960 from a regime where the distribution was always represented by a steady characteristic function to a new state where the distribution dilates as time goes on. This suggests that the rule that was governing the statistical behavior of bilateral trade imbalances until the 60's abruptly changed to a new form persistent in the last decades. In the new regime, the figures for the different years collapse into a universal master curve when rescaled by the corresponding global gross domestic product value. This coupling points to an increased interdependence of world economies and its onset corresponds in time with the starting of the last globalization wave.Comment: Final versio

Increasing the value of research: a comparison of the literature on critical success factors for projects, IT projects and enterprise resource planning projects

Since the beginning of modern project management in the 1960s, academic researchers have sought to identify a definitive list of Critical Success Factors (CSFs), the key things that project managers must get right in order to deliver a successful product. With the advent of Information Technology (IT) projects and, more recently, projects to deliver Enterprise Resource Planning (ERP) systems, attention has turned to identifying definitive lists of CSFs for these more specific project types. The purpose of this paper is to take stock of this research effort by examining how thinking about each type of project has evolved over time, before producing a consolidated list of CSFs for each as a basis for comparison. This process reveals a high degree of similarity, leading to the conclusion that the goal of identifying a generic list of CSFs for project management has been achieved. Therefore, rather than continuing to describe lists of CSFs, researchers could increase the value of their contribution by taking a step forward and focusing on why, despite this apparent knowledge of how to ensure their success, ERP projects continue to fai

The amenity value of the Italian climate

The hedonic price literature suggests that locations with more favourable characteristics should display compensating wage and house price differentials. Estimates of the marginal willingness to pay for small changes in climate variables are derived using the hedonic price technique applied to Italian data. A hedonic price model was specified in terms of January and July averages. There exists considerable empirical support for the hypothesis that amenity values for climate are embedded in the labour and housing market. Italians would prefer a drier climate during the winter months, but higher summertime temperatures are shown to reduce welfare. These results may have relevance to the task of determining the economic impact of future climate change

Fear and perceived likelihood of victimization in the traditional and cyber settings

This study considers the influence of perceived likelihood, demographics (gender and education) and personality on fear of victimization and cyber-victimization using a survey design (N=159). The results suggest that perceived likelihood of victimization predicts fear of victimization in traditional contexts. Women tend to be more fearful of victimization in traditional and cyber contexts, confirming previous research. No group differences emerged in relation to education. Self-esteem and self-efficacy were not significant predictors of fear or perceived likelihood of victimization. However, perceived likelihood was a significant predictor of fear of victimization in traditional settings. This may suggest that different variables (such as awareness of vulnerability) may play a role in fear of victimization in cyber settings. Further group comparisons revealed that fear of victimization and cybervictimization depended on whether or not participants reported high or low perceived likelihood of victimization and internet use. Higher internet use was associated with greater fear of victimization, especially in combination with greater perceived likelihood of victimization. This may suggest an exposure effect, in that being online more frequently may also increase awareness of cyber incidents

Modelling distributed lag effects in mortality and air pollution studies: the case of Santiago

Most of the epidemiological literature on air pollution and mortality deals only with single or dual pollutant models whose results are hard to interpret and of questionable value from the policy perspective. In addition, much of the existing literature deals only with the very short-term effects of air pollution whereas policy makers need to know when, whether and to what extent pollution-induced increases in mortality counts are reversed. This involves modelling the infinite distributed lag effects of air pollution. Borrowing from econometrics this paper presents a method by which the infinite distributed lag effects can be estimated parsimoniously but plausibly estimated. The paper presents a time series study into the relationship between ambient levels of air pollution and daily mortality counts for Santiago employing this technique which confirms that the infinite lag effects are highly significant. It is also shown that day to day variations in NO2 concentrations and in the concentrations of both fine and coarse particulates are associated with short-term variations in death rates. These findings are made in the context of a model that simultaneously includes six different pollutants. Evidence is found pointing to the operation of a very short term harvesting effect

Valuing congestion costs in the British Museum

Museums are potentially congestible resources because the exhibits they contain are, in any relevant sense of the word, irreproducible. Insofar as visitor congestion diminishes the value of individuals’ visits it constitutes an additional reason for charging for admission to museums, albeit one not previously considered. A policy of free access to a museum containing unique treasures may dissipate the economic benefits of the museum. Within the context of an empirical study undertaken for the British Museum using stated preference techniques it is shown that the congestion cost posed by the marginal visitor is quite high. Notwithstanding the argument that visits to the museum may possess external benefits, this points to the desirability of instigating charges for admission. Furthermore, it is shown that the marginal congestion cost decreases at least over a range as visitor numbers increase. In other words beyond certain levels introducing more visitors does not worsen congestion. This suggests that, contrary to what is often assumed, charging more during periods of high demand may be undesirable. Insofar as congestion is a widespread phenomenon in important museums, galleries and sites of historical heritage the issues raised in this paper as well as the methodology devised to determine congestion costs could have widespread application