Does the Moment-Generating Function Characterize a Distribution?

It is shown that two visibly distinct distributions can have almost identical moment-generating functions.     

Optimally robust estimators in generalized Pareto models

In this paper, we study the robustness properties of several procedures for the joint estimation of shape and scale in a generalized Pareto model. The estimators that we primarily focus upon, most bias robust estimator (MBRE) and optimal MSE-robust estimator (OMSE), are one-step estimators distinguished as optimally robust in the shrinking neighbourhood setting; that is, they minimize the maximal bias, respectively, on such a specific neighbourhood, the maximal mean squared error (MSE). For their initialization, we propose a particular location–dispersion estimator, MedkMAD, which matches the population median and kMAD (an asymmetric variant of the median of absolute deviations) against the empirical counterparts. These optimally robust estimators are compared to the maximum-likelihood, skipped maximum-likelihood, Cramér–von-Mises minimum distance, method-of-medians, and Pickands estimators. To quantify their deviation from robust optimality, for each of these suboptimal estimators, we determine the finite-sample breakdown point and the influence function, as well as the statistical accuracy measured by asymptotic bias, variance, and MSE – all evaluated uniformly on shrinking neighbourhoods. These asymptotic findings are complemented by an extensive simulation study to assess the finite-sample behaviour of the considered procedures. The applicability of the procedures and their stability against outliers are illustrated for the Danish fire insurance data set from the package evir.     

From design to operations: a process management life-cycle performance measurement system for Public-Private Partnerships

Public–Private Partnerships (PPPs) have become a critical vehicle for delivering infrastructure worldwide. Yet, the use of such a procurement strategy has received considerable criticism, as they have been prone to experiencing time/cost overruns and during their operation poorly managed. A key issue contributing to the poor performance of PPPs is the paucity of an effective and comprehensive performance measurement system. There has been a tendency for the performance of PPPs to be measured based on their ex-post criteria of time, cost and quality. Such criteria do not accommodate the complexities and lifecycle of an asset. In addressing this problem, the methodology of sequential triangulation is used to develop and examine the effectiveness of a ‘Process Management Life Cycle Performance Measurement System’. The research provides public authorities and private-sector entities embarking on PPPs with a robust mechanism to effectively measure, control and manage their projects’ life cycle performances, ensuring the assets are ‘future proofed’.     

Let's Call it Quits: Break‐Even Effects in the Decision to Stop Taking Risks

“Chasing” behavior, whereby individuals, driven by a desire to break even, continue a risky activity (RA) despite incurring large losses, is a commonly observed phenomenon. We examine whether the desire to break even plays a wider role in decisions to stop engaging in financially motivated RA in a naturalistic setting. We test hypotheses, motivated by this research question, using a large data set: 707,152 transactions of 5,379 individual financial market spread traders between September 2004 and April 2013. The results indicate strong effects of changes in wealth around the break‐even point on the decision to cease an RA. An important mediating factor was the individual's historical long‐term performance. Those with a more profitable trading history were less affected by a fall in cash balance below the break‐even point compared to those who had been less profitable. We observe that break‐even points play an important role in the decision of nonpathological risk takers to stop RAs. It is possible, therefore, that these nonpathological cognitive processes, when occurring in extrema, may result in pathological gambling behavior such as “chasing.” Our data set focuses on RAs in financial markets and, consequently, we discuss the implications for institutions and regulators in the effective management of risk taking in markets. We also suggest that there may be a need to consider carefully the nature and role of “break‐even points” associated with a broader range of nonfinancially‐focused risk‐taking activities, such as smoking and substance abuse.     

What is this moment we are caught in?

Our response to the question ‘What is this moment we are caught in?' is articulated through our collaborative reading of Berlant's (2011) Cruel Optimism (Durham, NC: Duke University Press). Cruel optimism, Berlant suggests, is a desire for something that undermines its own potentiality. As queer academics we expose the cruelty of our desires to live a good academic life, and we do so from our different positions as postdoctoral fellow, tenured academic and PhD candidate. In labouring to consolidate relationships and practices that hold the promise of our own sustainability, we give accounts of the material and affective work we perform to constitute what Berlant calls an intimate public, a collective space of mediation that functions as a key tactic to manage our academic life. These accounts take the form of three vignettes, each inflected by the specificities of our different positions and histories of becoming academics. We use Berlant as a point of departure to both interrogate practices of self‐management and find possibilities for a collective response to the moments in which we find ourselves caught.     

Colonization and habitat selection of a declining farmland species in urban areas

Despite the accelerating global urbanization and its associated implications for wildlife and humans, we know little about the biology of urban ecosystems. Here, we investigated colonization and habitat selection of the European hare (Lepus europaeus), a declining farmland species, in urban areas in Denmark, using a combination of citizen science data and transect counts. Further, we estimated the population density of urban hares in Aarhus, Denmark’s second largest city. Our results provide the first evidence that hares have established populations in urban areas, potentially in response to decreasing habitat quality in rural areas due to agricultural intensification. The hare density in Aarhus was ca. 8 hares per km², which is comparable to or slightly higher than hare abundance estimates from various pastural areas in Europe, suggesting that urban areas provide suitable habitat for hares. Hare habitat selection was generally associated with areas consisting of large lawns, such as high buildings and parks, which potentially provide high-quality forage throughout the year. Considering the increasing expansion of urban areas and deteriorating habitat quality of agricultural areas, urban planning that incorporates habitat requirements for wildlife could help to support urban animal populations, especially for species of conservation concern.

     

Young people and the gendered and aesthetic dimensions of ‘enterprise’: stories from a ‘Rust Belt’ city

ABSTRACT

In the ‘Rust Belt’ city of Geelong in Victoria, Australia, discourses of young people’s enterprise and innovation provide a counter-narrative to the prevailing material and symbolic consequences of industrial decline, job losses, and the growing insecurity of employment and income. GT Magazine is a weekly, large circulation magazine in Geelong with a significant focus on the activities and aspirations of enterprising young people. In this paper, we examine, by utilising techniques of content analysis and discourse analysis, the particular ways in which young people’s innovation and enterprise are framed and enacted in GT Magazine. Our analysis reveals that ‘youth’ and ‘enterprise’ are, in GT Magazine, given an embodied form that is powerfully marked by aestheticised, normalised enactments of gender, class and race. In doing this work, we make productive contributions to three key themes in contemporary youth studies: new work orders and the youthful self as enterprise; the gendered and aesthetic dimensions of affective labour in these new work orders; and the emerging spatial turn to examine young people's embodied, place-based experiences of employment and enterprise. We seek to make problematic the sense that solutions to multiple disruptions and crises in capitalism and the environment are to be found in young people’s enterprise. Particularly when that enterprise is given form in ways that are aestheticised, gendered, classed, individualised and responsibilised.     

Fiddling while the planet burns? COP25 in perspective

ABSTRACT

With fires, storms, social protests, and climate strikes sweeping the world, 2019 should have been a tipping point in how the world responds to global heating. This was the backdrop to the COP25 climate change summit which took place in Madrid in December 2019. This paper assesses the outcomes of the meeting and the path towards the critically important meeting in Glasgow at the end of 2020. It analyses and explains the key points of contention over levels of ambition, the rules which should govern global carbon markets and sensitive issues such as loss and damage associated with the impacts of climate change. The analysis is situated within a broader geopolitical and economic context of right-wing populism, deepening forms of marketization and financialization of responses to climate change and against a background of a world increasingly feeling the effects of the climate crisis.     

Probabilistic Analysis of Dam Accidents Worldwide: Risk Assessment for Dams of Different Purposes in OECD and Non-OECD Countries with Focus on Time Trend Analysis

This study presents probabilistic analysis of dam accidents worldwide in the period 1911–2016. The accidents are classified by the dam purpose and by the country cluster, where they occurred, distinguishing between the countries of the Organization for Economic Cooperation and Development (OECD) and nonmember countries (non-OECD without China). A Bayesian hierarchical approach is used to model distributions of frequency and severity for accidents. This approach treats accident data as a multilevel system with subsets sharing specific characteristics. To model accident probabilities for a particular dam characteristic, this approach samples data from the entire data set, borrowing the strength across data set and enabling to model distributions even for subsets with scarce data. The modelled frequencies and severities are combined in frequency-consequence curves, showing that accidents for all dam purposes are more frequent in non-OECD (without China) and their maximum consequences are larger than in OECD countries. Multipurpose dams also have higher frequencies and maximum consequences than single-purpose dams. In addition, the developed methodology explicitly models time dependence to identify trends in accident frequencies over the analyzed period. Downward trends are found for almost all dam purposes confirming that technological development and implementation of safety measures are likely to have a positive impact on dam safety. The results of the analysis provide insights for dam risk management and decision-making processes by identifying key risk factors related to country groups and dam purposes as well as changes over time.