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Standard Assumptions (standard + assumption)
Selected AbstractsAnalysing risk attitudes to timeHEALTH ECONOMICS, Issue 6 2010Adam Oliver Abstract The assumption of risk neutrality over discounted life years underlies the standard QALY model of individual preferences over health outcomes, and is thus implicitly assumed by NICE and other health technology advisory bodies worldwide. The primary objective of this article is to report a study to test the assumption in a convenience sample of 30 respondents with use of the probability equivalence version of the standard gamble. The results indicate considerable risk aversion over life years, and therefore call into question the standard assumption of risk neutrality in practical cost-utility analyses (CUA). A secondary objective is to observe whether risk aversion can be reduced through the use of the lottery equivalents method, under the hypothesis that the gambling effect can be lessened with this instrument. In a separate convenience sample of 40 respondents, however, the observed level of risk aversion was at least that seen in the standard gamble. Further research is warranted to ascertain whether risk aversion over discounted life years is a generalisable concern. Copyright © 2009 John Wiley & Sons, Ltd. [source] Experimental analysis of compaction of concrete and mortarINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 15 2001Nicolas Burlion Abstract Compaction of concrete is physically a collapse of the material porous microstructure. It produces plastic strains in the material and, at the same time, an increase of its bulk modulus. This paper presents two experimental techniques aimed at obtaining the hydrostatic response of concrete and mortar. The first one is a uniaxial confined compression test which is quite simple to implement and allows to reach hydrostatic pressures of about 600 MPa. The specimen size is large enough so that concrete with aggregate sizes up to 16 mm can be tested. The second one is a true hydrostatic test performed on smaller (mortar) specimens. Test results show that the hydrostatic response of the material is elasto-plastic with a stiffening effect on both the tangent and unloading bulk moduli. The magnitude of the irreversible volumetric strains depends on the initial porosity of the material. This porosity can be related in a first approximation to the water/cement ratio. A comparison of the hydrostatic responses obtained from the two testing techniques on the same material show that the hydrostatic response of cementitious materials cannot be uncoupled from the deviatoric response, as opposed to the standard assumption in constitutive relations for metal alloys. This feature should be taken into account in the development of constitutive relations for concrete subjected to high confinement pressures which are needed in the modelling of impact problems. Copyright © 2001 John Wiley & Sons, Ltd. [source] AGGLOMERATION VERSUS PRODUCT VARIETY: IMPLICATIONS FOR REGIONAL INEQUALITIES,JOURNAL OF REGIONAL SCIENCE, Issue 5 2006Kristian Behrens ABSTRACT We investigate how cross-country differences in firms' fixed set-up costs affect the trade-off between global efficiency and spatial equity. Our analysis reveals that the standard assumption of symmetry in set-up costs masks the existence of an interesting effect: the range of available varieties depends on the spatial distribution of firms. In such a setting, where the market outcome leads to excessive agglomeration in the symmetric case, a planner may opt for asymmetric set-up costs and even more agglomeration. We show that the planner will always favor lower set-up costs in the large country with more agglomeration when the consumer's marginal preference for variety is high, or with less agglomeration when the consumer's marginal preference for variety is low. [source] Bootstrapping a weighted linear estimator of the ARCH parametersJOURNAL OF TIME SERIES ANALYSIS, Issue 3 2009Arup Bose Abstract., A standard assumption while deriving the asymptotic distribution of the quasi maximum likelihood estimator in ARCH models is that all ARCH parameters must be strictly positive. This assumption is also crucial in deriving the limit distribution of appropriate linear estimators (LE). We propose a weighted linear estimator (WLE) of the ARCH parameters in the classical ARCH model and show that its limit distribution is multivariate normal even when some of the ARCH coefficients are zero. The asymptotic dispersion matrix involves unknown quantities. We consider appropriate bootstrapped version of this WLE and prove that it is asymptotically valid in the sense that the bootstrapped distribution (given the data) is a consistent estimate (in probability) of the distribution of the WLE. Although we do not show theoretically that the bootstrap outperforms the normal approximation, our simulations demonstrate that it yields better approximations than the limiting normal. [source] Lower confidence limits for process capability indices Cp and Cpk when data are autocorrelatedQUALITY AND RELIABILITY ENGINEERING INTERNATIONAL, Issue 6 2009Cynthia R. Lovelace Abstract Many organizations use a single estimate of Cp and/or Cpk for process benchmarking, without considering the sampling variability of the estimators and how that impacts the probability of meeting minimum index requirements. Lower confidence limits have previously been determined for the Cp and Cpk indices under the standard assumption of independent data, which are based on the sampling distributions of the index estimators. In this paper, lower 100(1-,)% confidence limits for Cp and Cpk were developed for autocorrelated processes. Simulation was used to generate the empirical sampling distribution of each estimator for various combinations of sample size (n), autoregressive parameter (,), true index value (Cp or Cpk), and confidence level. In addition, the minimum values of the estimators required in order to meet quality requirements with 100(1-,)% certainty were also determined from these empirical sampling distributions. These tables may be used by practitioners to set minimum capability requirements for index estimators, rather than true values, for the autocorrelated case. The implications of these results for practitioners will be discussed. Copyright © 2008 John Wiley & Sons, Ltd. [source] A data assimilation method for log-normally distributed observational errorsTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 621 2006S. J. Fletcher Abstract In this paper we change the standard assumption made in the Bayesian framework of variational data assimilation to allow for observational errors that are log-normally distributed. We address the question of which statistic best describes the distribution for the univariate and multivariate cases to justify our choice of the mode. From this choice we derive the associated cost function, Jacobian and Hessian with a normal background. We also find the solution to the Jacobian equal to zero in both model and observational space. Given the Hessian that we derive, we define a preconditioner to aid in the minimization of the cost function. We extend this to define a general form for the preconditioner, given a certain type of cost function. Copyright © 2006 Royal Meteorological Society [source] AN ANALYSIS OF DURATION ON THE DISABILITY SUPPORT PENSION PROGRAM,AUSTRALIAN ECONOMIC PAPERS, Issue 2 2006LIXIN CAI The paper examines the factors that determine the duration on the Disability Support Pension (DSP) program using administrative data. We estimate two models based on two competing assumptions: the first model takes the standard assumption in duration models that all recipients will eventually leave the program. The second one takes into account the possibility that there may be some recipients who will never recover from their disabilities and hence not leave the program. Both models indicate that female recipients, recipients who enter DSP at a very young or very old age, recipients with a partner on income support, and recipients who transfer from unemployment benefits have the potential of a longer DSP duration. [source] Capital gains tax and the capital asset pricing modelACCOUNTING & FINANCE, Issue 2 2003Martin Lally Abstract This paper develops a version of the Capital Asset Pricing Model that views dividend imputation as affecting company tax and assumes differential taxation of capital gains and ordinary income. These taxation issues aside, the model otherwise rests on the standard assumptions including full segmentation of national capital markets. It also treats dividend policy as exogenously determined. Estimates of the cost of equity based on this model are then compared with estimates based on the version of the CAPM typically applied in Australia, which differs only in assuming equality of the tax rates on capital gains and ordinary income. The differences between the estimates can be material. In particular, with a high dividend yield, allowance for differential taxation can result in an increase of two to three percentage points in the estimated cost of equity. The overall result obtained here carries over to a dividend equilibrium, in which firms choose a dividend policy that is optimal relative to the assumed tax structure. [source] A reexamination of corporate risks under shadow costs of incomplete informationINTERNATIONAL JOURNAL OF FINANCE & ECONOMICS, Issue 1 2001Mondher Bellalah G3; G31; G32; G33 Abstract The valuation of the firm and its assets has been done for a long time in the classic context of complete information. Several empirical tests of the main valuation methods reveal a divergence between theoretical prices and observed prices. These deviations might be explained by the standard assumptions of complete information. It is possible to introduce information uncertainty as done by Merton and by Bellalah in the reexamination of corporate risks in the presence of information costs. The concept of risk is useful in modelling the value of the firm and its business risk and in the definition of the required rates of return and the cost of capital of corporations. However, the main well-known results ignore information uncertainty as defined by Merton. Using the main results from the study of Modigliani and Miller and the implications of Merton's model, we give expressions for the cost of capital and the value of the firm's equity and debt in the presence of information costs. We reexamine the relationships between interrelated risks in the same context. We introduce information costs in the computation of the cost of capital and in the pricing of equity in an option framework. When there are no information costs, the main relationships reduce to the classic results in the literature. Copyright © 2001 John Wiley & Sons, Ltd. [source] Artificial boundary conditions for viscoelastic flowsMATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 8 2008Sergueï A. Nazarov Abstract The steady three-dimensional exterior flow of a viscoelastic non-Newtonian fluid is approximated by reducing the corresponding nonlinear elliptic,hyperbolic system to a bounded domain. On the truncation surface with a large radius R, nonlinear, local second-order artificial boundary conditions are constructed and a new concept of an artificial transport equation is introduced. Although the asymptotic structure of solutions at infinity is known, certain attributes cannot be found explicitly so that the artificial boundary conditions must be constructed with incomplete information on asymptotics. To show the existence of a solution to the approximation problem and to estimate the asymptotic precision, a general abstract scheme, adapted to the analysis of coupled systems of elliptic,hyperbolic type, is proposed. The error estimates, obtained in weighted Sobolev norms with arbitrarily large smoothness indices, prove an approximation of order O(R,2+,), with any ,>0. Our approach, in contrast to other papers on artificial boundary conditions, does not use the standard assumptions on compactly supported right-hand side f, leads, in particular, to pointwise estimates and provides error bounds with constants independent of both R and f. Copyright © 2007 John Wiley & Sons, Ltd. [source] Populating the Galaxy with low-mass X-ray binariesMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 3 2006Paul D. Kiel ABSTRACT We perform binary population-synthesis calculations to investigate the incidence of low-mass X-ray binaries (LMXBs) and their birth rate in the Galaxy. We use a binary-evolution algorithm that models all the relevant processes including tidal circularization and synchronization. Parameters in the evolution algorithm that are uncertain and may affect X-ray binary formation are allowed to vary during the investigation. We agree with previous studies that under standard assumptions of binary evolution the formation rate and number of black hole (BH) LMXBs predicted by the model are more than an order of magnitude less than what is indicated by observations. We find that the common-envelope process cannot be manipulated to produce significant numbers of BH LMXBs. However, by simply reducing the mass-loss rate from helium stars adopted in the standard model, to a rate that agrees with the latest data, we produce a good match to the observations. Including LMXBs that evolve from intermediate-mass systems also leads to favourable results. We stress that constraints on the X-ray binary population provided by observations are used here merely as a guide as surveys suffer from incompleteness and much uncertainty is involved in the interpretation of results. [source] COALITION FORMATION IN A GLOBAL WARMING GAME: HOW THE DESIGN OF PROTOCOLS AFFECTS THE SUCCESS OF ENVIRONMENTAL TREATY-MAKINGNATURAL RESOURCE MODELING, Issue 3 2006JOHAN EYCKMANS ABSTRACT. We combine new concepts of noncooperative coalition theory with an integrated assessment model on climate change to analyze the impact of different protocol designs on the success of coalition formation. We analyze the role of "single versus multiple coalitions,""open versus exclusive membership,""no, weak and strong consensus about membership" and "no transfers versus transfers." First, we want to find out whether and how modifications of the standard assumptions affect results that are associated with the widely applied cartel formation game in the noncooperative game theoretic analysis of international environmental agreements. Second, we discuss normative policy conclusions that emerge from the various modifications. Third, we confront our results with evidence on past international environmental treaties and derive an agenda for future research. [source] Outside the glass case: The social life of urban heritage in KyotoAMERICAN ETHNOLOGIST, Issue 2 2009CHRISTOPH BRUMANN ABSTRACT Recent anthropological and other literature tends to assume that the uses of heritage in modern societies lead to the falsification, petrification, desubstantiation, and enclosure of the things and practices so designated. Yet two traditions of Japan's ancient capital Kyoto,the historic town houses (kyô-machiya) that have found a new appreciation since the 1990s and the Gion matsuri, one of the most famous festivals of the nation,contradict these assumptions. Their well-documented histories are not widely distorted; they are not forever fixed but allowed to evolve; they are valued not only for their traditionality but also for other, substantive qualities; and their appreciation is not dominated by a concern for social boundaries. This is influenced by the urban, relatively sophisticated and cosmopolitan background of both traditions, as it is in parallel cases elsewhere. Greater attention to the perspectives of their carriers, however, will very likely show that the social uses of other traditions too are more complex than the standard assumptions lead one to believe. [Japan, cultural heritage, invention of tradition, vernacular architecture, festivals, urban anthropology] [source] Do Anomalies Disappear in Repeated Markets?*THE ECONOMIC JOURNAL, Issue 486 2003Graham Loomes There is some evidence that, as individuals participate in repeated markets, ,anomalies' tend to disappear. One interpretation is that individuals , particularly marginal traders , are learning to act on underlying preferences which satisfy standard assumptions. An alternative interpretation, the ,shaping' hypothesis, is that individuals' preferences are adjusting in response to cues given by market prices. The paper reports an experiment designed to discriminate between these hypotheses with particular reference to the disparity between willingness to pay and willingness to accept. [source] Greenhouse gas and groundwater recharge abatement benefits of tree crops in south-western Australian farming systemsAUSTRALIAN JOURNAL OF AGRICULTURAL & RESOURCE ECONOMICS, Issue 2 2003Elizabeth Petersen The indirect benefits of a commercial tree crop for greenhouse gas and groundwater recharge abatement are analysed. Oil mallees are introduced into a whole-farm linear programming model as a source of income, an offset to greenhouse gas emissions from the mixed sheep and cropping enterprises and as a source of groundwater recharge abatement. The profitability of oil mallees is found to be very sensitive to the discount rate, yield and price assumptions and the relative profitability of other farm enterprises (especially the wool enterprise). Under standard assumptions where oil mallees are profitable, the trees significantly reduced greenhouse gas emissions and groundwater recharge and the farm remains profitable. If farm-level policies are introduced for greenhouse gas abatement, without tree crops or some other technological change, the current farming systems would fail and be replaced by alternative land uses. [source] | |||||||||||||||||||