175 research outputs found

    Scenario Analysis with Recursive Utility: Dynamic Consumption Plans for Charitable Endowments

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    We determine optimal consumption paths under a series of returns scenarios for charitable endowments with distinct tastes over investment risk and inter-temporal substitution. Charities typically prefer smooth consumption paths but are investment-risk tolerant. Using a recursive, Kreps-Porteus utility function, we model the optimal disbursement from an infinitely-lived charitable trust, then, allowing a general form for the returns density, we apply stochastic dominance relations to estimate income/substitution effects whereby a change in future returns influences the current consumption rate. The elasticity of intertemporal substitution rather than risk aversion is key: optimal consumption rises or falls as the elasticity diverges from one.recursive utility; stochastic dominance; inter-temporal choice

    Discounting and Consumption Over an Uncertain Horizon: Draw-Down Plans for Family Trusts

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    Individuals, endowments and trusts face uncertain lifetimes. When the planning horizon of an entity is stochastic and Pareto distributed, hyperbolic discounting and time-varying consumption rates are optimal. We derive expressions for the optimal rate of consumption (draw-down) from wealth for family trusts facing positive probabilities of extinction at each generation. Using birth statistics for the UK, we compute family extinction probabilities and show that they are well-approximated by a Pareto distribution, hence family trusts will discount hyperbolically. Numerically optimised consumption paths for family trusts with CRRA preferences are decreasing but always higher than for infinitely-lived trusts.family extinction; hyperbolic discounting; inter-temporal choice

    Economic Rationality, Risk Presentation, and Retirement Portfolio Choice.

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    This research studies the propensity of individuals to violate implications of expected utility maximization in allocating retirement savings within a compulsory de- �ned contribution retirement plan. The paper develops the implications and describes the construction and administration of a discrete choice experiment to almost 1200 members of Australias mandatory retirement savings scheme. The experiment �nds overall rates of violation of roughly 25%, and substantial variation in rates, depend- ing on the presentation of investment risk and the characteristics of the participants. Presentations based on frequency of returns below or above a threshold generate more violations than do presentations based on the probability of returns below or above thresholds. Individuals with low numeracy skills, assessed as part of the ex-periment, are several times more likely to violate implications of the conventional expected utility model than those with high numeracy skills. Older individuals are substantially less likely to violate these restrictions, when risk is presented in terms of event frequency, than are younger individuals. The results pose significant questions for public policy, in particular compulsory de�ned contribution retirement schemes, where the future welfare of participants in these schemes depends on quantitative decision-making skills that a signi�cant number of them do not possess.discrete choice; retirement savings; investment risk; household finance; financial literacy

    Benefits management : lost or found in translation

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    It is now about 25 years since the emergence of Benefits Management (BM), but hitherto it has had limited impact on project management and even less on general management practices. This is despite evidence that a focus on benefits improves the success rate of projects and programmes. One of the areas for research to explain the limited uptake concerns the spread of knowledge on BM and its adoption by organisations. The theoretical lens of translation is used to examine this issue, which focuses on the processes through which management ideas spread and influence management practice. The global development of BM is traced to identify the changes in translation processes over time and the current geographical patterns of usage. This analysis is used in conjunction with the limited evidence available on translation processes at the level of the organisation to identify key factors for the impact of BM in the future

    A unified view of benefits management/benefits realization management to be integrated into PMI standards

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    Measures for benefits realization.

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    GausSN: Bayesian Time-Delay Estimation for Strongly Lensed Supernovae

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    We present GausSN, a Bayesian semi-parametric Gaussian Process (GP) model for time-delay estimation with resolved systems of gravitationally lensed supernovae (glSNe). GausSN models the underlying light curve non-parametrically using a GP. Without assuming a template light curve for each SN type, GausSN fits for the time delays of all images using data in any number of wavelength filters simultaneously. We also introduce a novel time-varying magnification model to capture the effects of microlensing alongside time-delay estimation. In this analysis, we model the time-varying relative magnification as a sigmoid function, as well as a constant for comparison to existing time-delay estimation approaches. We demonstrate that GausSN provides robust time-delay estimates for simulations of glSNe from the Nancy Grace Roman Space Telescope and the Vera C. Rubin Observatory's Legacy Survey of Space and Time (Rubin-LSST). We find that up to 43.6% of time-delay estimates from Roman and 52.9% from Rubin-LSST have fractional errors of less than 5%. We then apply GausSN to SN Refsdal and find the time delay for the fifth image is consistent with the original analysis, regardless of microlensing treatment. Therefore, GausSN maintains the level of precision and accuracy achieved by existing time-delay extraction methods with fewer assumptions about the underlying shape of the light curve than template-based approaches, while incorporating microlensing into the statistical error budget rather than requiring post-processing to account for its systematic uncertainty. GausSN is scalable for time-delay cosmography analyses given current projections of glSNe discovery rates from Rubin-LSST and Roman.Comment: 18 pages, 12 figures, submitted to MNRA

    Resolution of the clinical features of tyrosinemia following orthotopic liver transplantation for hepatoma

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    The clinical history before transplantation and subsequent clinical and biochemical course of 3 children and one adult with hereditary tyrosinemia treated by orthotopic hepatic transplantation is described. All four patients are now free of their previous dietary restrictions and appear to be cured of both their metabolic disease and their hepatic neoplasm. © 1986 Elsevier Science Publishers B.V. All rights reserved
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