1,721,526 research outputs found
The Meaning of Death: Some Simulations of a Model of Healthy and Unhealthy Consumption
No full textSimulations of a model of healthy and unhealthy consumption are used to investigate the impact of various terminal conditions on life-span, pathways of health-related consumption and health. A model in which life-span and the ‘death’ stock of health are fixed is compared to versions in which (i) the ‘death’ stock of health is freely chosen; (ii) life-span is freely chosen; (iii) both the ‘death’ stock of health and life-span are freely chosen. The choice of terminal conditions has a striking impact on optimal plans. Results are discussed with reference to the existing demand for health literature and illustrate the application of iterative processes to determine optimal life-span, the role played by the marginal value of health capital in determining optimal plans, and the importance of checking the second-order conditions for the optimal choice of life-span
Optimal plans and timing under additive transformations to rewards
No full textThe nature and role of additive transformations to rewards are elucidated for a general class of deterministic, nonautonomous, optimal control problems with many state and control variables. Conditions relating to the optimal choice of initial and terminal times and initial and terminal values of state variables are identified such that additive transformations affect optimal plans. General comparative static results are derived and the framework is extended to cover two common classes of stochastic control problems. Three applications are presented: the canonical adjustment cost model of a firm, a stochastic extension of an irreversible pollution accumulation problem with regime-switching, and an extension of a lifecycle model of retirement in which an agent’s retirement wealth evolves stochastically
Biases in bias elicitation
No full textWe consider the biases that can arise in bias elicitation when expert assessors make random errors. After presenting a general framework of the phenomenon, we illustrate it for two examples: the case of omitting variables bias and that of the bias arising in adjusting relative risks. Results show that, even when assessors’ elicitations of bias have desirable properties, the nonlinear nature of biases can lead to elicitations of bias that are, themselves, biased. We show the corrections which can be made to remove this bias and discuss the implications for the applied literature which employs these methods
Dynamic, economic approaches to HTA under uncertainty. WP Series University of Verona Department of Economics (ISSN 2036-2919), 03/2011
No full textA simple, two period framework is used to interpret existing contributions to the literature on decision rules for HTA under uncertainty and to contrast them with a dynamic, economic model solved using backward induction
Inference of the magnetospheric plasma mass density from field line resonances: A test using a plasmasphere model
No full textUsing field-aligned ion density profiles from a physical-numerical model of the plasmasphere, we investigated the reliability of techniques which use field line resonance measurements to remotely sense the plasmaspheric mass density rho, over L=1.6-3.4. We find that the common assumption of some functional law for the variation of rho along different field lines may lead to distorted profiles of the equatorial density rho(o) as inferred from the observed fundamental field line eigenfrequency. The tests show that for midlatitude field lines (2.3<L<3.4) a radial power law with an index m congruent to 1 might be appropriate for a large variety of solar and geomagnetic conditions, and this index well represents the mass density dependence on the outer part of the field line. Indeed, an accurate integral expression of the field line eigenperiod demonstrates that the low-altitude plasma tube provides a negligible contribution to the eigenperiod. However, at lower latitudes, higher m values are necessary to obtain correct estimates of rho(o). In this case m represents only an average index, not related to any particular variation of rho along the field line. This effective index is also significantly dependent on solar activity conditions and local time. It turns out that inferred temporal variations of rho(o) at a given low L-shell can be significantly overestimated when a fixed functional dependence for the field-aligned mass density is assumed. The performance of more sophisticated techniques which use higher harmonics is also examined
The role of tobacco taxes in starting and quitting smoking: duration analysis of British data
No full textThe annual 5% increase in tobacco taxes in real terms proposed in the recent White Paper on smoking has reaffirmed the commitment of successive UK Governments to above-inflation increases in tobacco taxation to encourage people to stop smoking. This paper presents evidence on the determinants of starting and quitting smoking by using data from the British Health and Lifestyle Survey and is the first to identify tax elasticities for starting and quitting smoking using British data. Self-reported individual smoking histories are coupled with a long time series for the tax rate on cigarettes to construct a longitudinal data set. Estimates are obtained for the effect of above-inflation tax rises on the age of starting smoking and the number of years of smoking. The estimates of the tax elasticity of the age of starting smoking are 0.16 for men and 0.08 for women. The estimates of the tax elasticity of quitting are −0.60 for men and −0.46 for women. These are robust to different specifications
Corrigendum: The role of tobacco taxes in starting and quitting smoking: duration analysis of British data
No full textDynamic, economic approaches to HTA under uncertainty
No full textA simple, two period framework is used to interpret existing contributions to the literature on decision rules for HTA under uncertainty and to contrast them with a dynamic, economic model solved using backward induction
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