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141.
Measuring credibility of compensatory preference statements when trade-offs are interval determined 总被引:1,自引:0,他引:1
This paper studies how an overall fuzzy preference relation can be constructed in the compensatory context of the simple additive difference model, when imprecision on the trade-offs has to be taken into account. Three credibility indices of preferences are analysed and illustrated by a numerical example. Arguments are presented supporting the use of the third index, for which an interesting transitivity property (which was an open problem) is proved. 相似文献
142.
143.
Finite mixture models with concomitant information: assessing diagnostic criteria for diabetes 总被引:1,自引:0,他引:1
T. J. Thompson P. J. Smith & J. P. Boyle 《Journal of the Royal Statistical Society. Series C, Applied statistics》1998,46(3):393-404
The World Health Organization (WHO) diagnostic criteria for diabetes mellitus were determined in part by evidence that in some populations the plasma glucose level 2 h after an oral glucose load is a mixture of two distinct distributions. We present a finite mixture model that allows the two component densities to be generalized linear models and the mixture probability to be a logistic regression model. The model allows us to estimate the prevalence of diabetes and sensitivity and specificity of the diagnostic criteria as a function of covariates and to estimate them in the absence of an external standard. Sensitivity is the probability that a test indicates disease conditionally on disease being present. Specificity is the probability that a test indicates no disease conditionally on no disease being present. We obtained maximum likelihood estimates via the EM algorithm and derived the standard errors from the information matrix and by the bootstrap. In the application to data from the diabetes in Egypt project a two-component mixture model fits well and the two components are interpreted as normal and diabetes. The means and variances are similar to results found in other populations. The minimum misclassification cutpoints decrease with age, are lower in urban areas and are higher in rural areas than the 200 mg dl-1 cutpoint recommended by the WHO. These differences are modest and our results generally support the WHO criterion. Our methods allow the direct inclusion of concomitant data whereas past analyses were based on partitioning the data. 相似文献
144.
Robert Aslett Robert J. Buck Steven G. Duvall Jerome Sacks & William J. Welch 《Journal of the Royal Statistical Society. Series C, Applied statistics》1998,47(1):31-48
In electrical engineering, circuit designs are now often optimized via circuit simulation computer models. Typically, many response variables characterize the circuit's performance. Each response is a function of many input variables, including factors that can be set in the engineering design and noise factors representing manufacturing conditions. We describe a modelling approach which is appropriate for the simulator's deterministic input–output relationships. Non-linearities and interactions are identified without explicit assumptions about the functional form. These models lead to predictors to guide the reduction of the ranges of the designable factors in a sequence of experiments. Ultimately, the predictors are used to optimize the engineering design. We also show how a visualization of the fitted relationships facilitates an understanding of the engineering trade-offs between responses. The example used to demonstrate these methods, the design of a buffer circuit, has multiple targets for the responses, representing different trade-offs between the key performance measures. 相似文献
145.
应用交通流宏观连续模型,模拟上下游信号灯作异步周期变化的协调信号灯路段的交通流动,经数值计算比较,选择改进Murman格式求解.结果表明:改进Murman格式能准确捕捉交通流中无振荡“激波”位置. 相似文献
146.
Suen W 《Journal of population economics》1997,10(4):443-461
This paper provides an overview of retirement patterns in Hong Kong on the basis of limited data. A censored regression model
is used to infer the retirement age from people‘s current retirement status and their current age. This model is equivalent
to a restricted probit model, and the interpretation of parameters is straightforward. The results clearly show a negative
income effect on the retirement decision. The retirement age seems to be positively related to lifetime earnings but negatively
related to the rate of decline of earnings with age.
JEL classification: C24, J14, J26
Received May 6, 1996 / Accepted February 5, 1997 相似文献
147.
The maximum likelihood estimation for the critical points of the failure rate and the mean residual life function are presented
in the case of mixture inverse Gaussian model. Several important data sets are analyzed from this point of view. For each
of the data sets, Bootstrapping is used to construct confidence intervals of the critical points. 相似文献
148.
Dietary and Inhalation Intake of Lead and Estimation of Blood Lead Levels in Adults and Children in Kanpur, India 总被引:1,自引:0,他引:1
This research was initiated to study lead levels in various food items in the city of Kanpur, India, to assess the dietary intake of lead and to estimate blood lead (PbB) levels, a biomarker of lead toxicity. For this purpose, sampling of food products, laboratory analysis, and computational exercises were undertaken. Specifically, six food groups (leafy vegetables, nonleafy vegetables, fruits, pulses, cereals, and milk), drinking water, and lead air concentration were considered for estimating lead intake. Results indicated highest lead content in leafy vegetables followed by pulses. Fruits showed low lead content and drinking water lead levels were always within tolerable limits. It was estimated that average daily lead intake through diet was about 114 microg/day for adults and 50 microg/day in children; tolerable limit is 250 microg/day for adults and 90 microg/day for children. The estimated lead intakes were translated into the resultant PbB concentrations for children and adults using a physiologically-based pharmacokinetic (PBPK) model. Monte Carlo simulation of PbB level variations for adults showed that probability of exceeding the tolerable limit of PbB (i.e.,10 microg/dL) was 0.062 for the pre-unleaded and 0.000328 for the post-unleaded gasoline period. The probability of exceeding tolerable limits in PbB level was reduced by a factor of 189 in the post-unleaded scenario. The study also suggested that in spite of the introduction of unleaded gasoline, children continue to be at a high risk (probability of exceeding 10 microg/dL = 0.39) because of a high intake of lead per unit body weight. 相似文献
149.
我国财务危机公司投资行为的财务特征分析 总被引:9,自引:0,他引:9
在引入一个简化的理性财务危机公司投资模型的基础上,论文分析了企业陷入财务危机后,债权人与债务人之间在期权博弈过程中,企业在投资策略的选择上会偏离正常的投资行为的财务特征。在此基础上,重点分析了我国经济转轨时期财务危机公司严重地过度投资和在债务重组过程中的盲目性、短期性和功利性及其形成的主要原因。企业的过度投资是内部人控制和银行债权弱化的具体体现,虚假的债务重组是将危机转嫁给企业债权人的真正动因。 相似文献
150.