Empirical Likelihood Based Synthetic Data Method for Censored Regression Analysis

In this article, we propose a new empirical likelihood method for linear regression analysis with a right censored response variable. The method is based on the synthetic data approach for censored linear regression analysis. A log-empirical likelihood ratio test statistic for the entire regression coefficients vector is developed and we show that it converges to a standard chi-squared distribution. The proposed method can also be used to make inferences about linear combinations of the regression coefficients. Moreover, the proposed empirical likelihood ratio provides a way to combine different normal equations derived from various synthetic response variables. Maximizing this empirical likelihood ratio yields a maximum empirical likelihood estimator which is asymptotically equivalent to the solution of the estimating equation that are optimal linear combination of the original normal equations. It improves the estimation efficiency. The method is illustrated by some Monte Carlo simulation studies as well as a real example.     

Constructing optimal router bit life sequential experimental designs: New results with a case study

Consider the experiment to improve router bit life as reported in Phadke (1986 Phadke, M. S. 1986. Design optimization case studies. AT &; T Technical Journal 65:51–68.[Crossref], [Web of Science ®] , [Google Scholar]). The goal of the experiment was to increase the life of the router bit before it gets dull, which causes excessive dust formation and consequent expensive cleaning operation to smooth the edges of the boards. A 32-run experimental design was used including seven two-level factors and two four-level factors (cf. Table 1). In this experiment and others, factorial designs with a mixture of two-level and μ( > 2)-level factors may be adopted. Sequential experiments composed of initial experiments and follow-up experiments are widely used to resolve ambiguities involving the aliasing of factorial effects. This article investigates the construction and theoretical properties of optimal designs for sequential experiments with a mixture of α two-level and β μ-level factors for the first time. Constructing optimal design for the router bit life sequential experiment will be discussed for a practical use. From the numerical results, it is found that using a uniform design as the initial experimental design for the router bit life experiment is highly recommended to get an efficient router bit life sequential experimental design. The novelty and significance of the work are evaluated by comparing our results to the existing literature.     

Optimal stimulation level theory, exploratory consumer behaviour and product adoption: an analysis of underlying structures across product categories

Research of the last decades focused on answering several questions in view of optimum stimulation theory. Which variables do influence general explorative tendencies such as risk taking, variety seeking, or curiosity-motivated behaviour and how do the general explorative tendencies effect the willingness to choose new or familiar products on a repurchase occasion? The approach of this research is the attempt to analyse a wide range of variables, which have successfully been tested to influence innovative behaviour, within one simultaneous model. This research is applied across different product-categories. It is confirming the nomological validity of OSL-theory including some contextual variables by attesting a principal consistency between all (six) models that have been established throughout the range of several examined product categories. The parameters between inherent factors do not contradict when comparing the single models with each other, parameter values do only differ slightly according to category-specific peculiarities. As a consequence of these results, an overall fairly good picture is drawn of what is behind the keenness for innovations of early adopters in general (regardless of the product category).     

Designs for two-colour microarray experiments

Summary.  Designs for two-colour microarray experiments can be viewed as block designs with two treatments per block. Explicit formulae for the A- and D-criteria are given for the case that the number of blocks is equal to the number of treatments. These show that the A- and D-optimality criteria conflict badly if there are 10 or more treatments. A similar analysis shows that designs with one or two extra blocks perform very much better, but again there is a conflict between the two optimality criteria for moderately large numbers of treatments. It is shown that this problem can be avoided by slightly increasing the number of blocks. The two colours that are used in each block effectively turn the block design into a row–column design. There is no need to use a design in which every treatment has each colour equally often: rather, an efficient row–column design should be used. For odd replication, it is recommended that the row–column design should be based on a bipartite graph, and it is proved that the optimal such design corresponds to an optimal block design for half the number of treatments. Efficient row–column designs are given for replications 3–6. It is shown how to adapt them for experiments in which some treatments have replication only 2.     

Response-adaptive randomization for survival trials: the parametric approach

Summary.  Few references deal with response-adaptive randomization procedures for survival outcomes and those that do either dichotomize the outcomes or use a non-parametric approach. In this paper, the optimal allocation approach and a parametric response-adaptive randomization procedure are used under exponential and Weibull distributions. The optimal allocation proportions are derived for both distributions and the doubly adaptive biased coin design is applied to target the optimal allocations. The asymptotic variance of the procedure is obtained for the exponential distribution. The effect of intrinsic delay of survival outcomes is treated. These findings are based on rigorous theory but are also verified by simulation. It is shown that using a doubly adaptive biased coin design to target the optimal allocation proportion results in more patients being randomized to the better performing treatment without loss of power. We illustrate our procedure by redesigning a clinical trial.     

关联理论看幽默及对中国相声的话语分析

以语用学中Speber和Wilson所提出的关联理论为框架,从认知角度来解释幽默话语。指出理解幽默话语是人们通过对已知信息推理的不断修改与重考而找到最佳关联——幽默的真谛。同时因读者在理解时付出更多努力而获得补偿——开怀一笑。并以此为基础对传统幽默——中国相声进行分析研究,指出其幽默根源在于错误推理的表面合理性,即说话者选择的最佳关联与听话者心中的最佳关联产生鲜明的对照和冲突,旨在探求关联性和幽默之间的关系,以期待对言语幽默有更好的理解和欣赏。     

Inequality of opportunity in the United Kingdom, 1991–2008

We investigate the extent to which the tax-and-transfer system of the United Kingdom equalizes opportunities for income attainment among citizens. Within the framework of Roemer’s theory of Equality of Opportunity, and using individual data from the British Household Panel Survey from 1991 to 2008, we calculate the tax rates necessary to equalize opportunities for different circumstances. We provide a ranking of these circumstances by the degree to which they influence income attainment. Although pre-fisc equality of opportunity increases over time, the tax rate necessary to equalize opportunities remains higher than the observed tax rate. Only under a relatively high labour supply elasticity the observed UK tax rate fares well in equalizing opportunities for income attainment.     

我国货币需求与总支出构成因素之间关系的实证研究

文章在建立了无约束误差修正模型的基础上,运用边限检验方法对我国货币需求与支出构成因素之间的关系进行了实证研究.结果表明我国货币需求M0、M1、M2和总支出构成因素之间存在长期稳定关系,支出的不同组成部分对我国货币需求有不同的影响,在短期内,投资支出对我国货币需求M1和M2都有显著影响.     

Managing Product Rollovers

We study the product rollover strategy decision, where a firm decides whether to phase out an old generation of a product to be replaced by a new with either a dual or single roll. Our model considers a final build of the old product and preannouncement of the new, and incorporates dynamic pricing and inventory decisions. We find that the optimal price path closely follows changes in reservation price curves for the two products over time. We also identify the drivers of the rollover strategy decision, finding that lower market risk (faster diffusion, higher market responsiveness to preannouncements) and higher performance improvement for the new generation are associated with the single roll strategy.