Estimation of a parametric function associated with the lognormal distribution

Estimation of the mean of the lognormal distribution has received much attention in the literature beginning with Finney (1941 Finney, D.J. (1941). On the distribution of a variate whose logarithm is normally distributed. Supp. J. Royal Stat. Soc. 7(2):155–161.[Crossref] , [Google Scholar]). The problem is of significant practical importance because of the ubiquitous use of log-transformation. In this article, we consider the estimation of a parametric function associated with the lognormal distribution of which the mean, median, and moments are special cases. We generalize various estimators from the literature for the mean to this parametric function and propose a new simple estimator. We present the estimators in a unified framework and use this framework to derive asymptotic expressions for their biases and mean square errors (MSEs). Next, we make asymptotic and small-sample comparisons via simulations between them in terms of their MSEs. Our proposed estimator outperforms many of the previously proposed estimators. A numerical example is given to illustrate the various estimators.     

Stakeholder-oriented brand management: A Venn-diagram approach to monitor brand associations

Adopting a multi-stakeholder perspective on brand management, this paper discusses different methodological approaches that allow for a cross-stakeholder evaluation of associations the brand triggers. Our main contribution is the proposal and illustration of a Venn-diagram approach as a simple-to-implement, yet insightful methodology to visualize findings from free association questions. This approach helps brand management understand and compare the associations attached to a brand by multiple stakeholders and their degree of match with management-desired brand associations. We illustrate the managerial relevance of this approach with results from an international study comparing brand associations desired by the management of a company with brand associations elicited by customers and employees, with some 1500 respondents respectively. For the particular case investigated, we find that management-desired associations may not (yet) be top-of-mind for customers, employees or both groups, while these groups hold (and partly share) associations not desired by the organization. The findings also show that specific types of associations are more likely to be top-of-mind with multiple stakeholders than others. We discuss how brand management should use the insights gained via this Venn-diagram approach in their brand-building efforts.     

Development of a Preliminary Framework for Informing the Risk Analysis and Risk Management of Nanoparticles

Decisions are often made even when there is uncertainty about the possible outcomes. However, methods for making decisions with uncertainty in the problem framework are scarce. Presently, safety assessment for a product containing engineered nano-scale particles is a very poorly structured problem. Many fields of study may inform the safety assessment of such particles (e.g., ultrafines, aerosols, debris from medical devices), but engineered nano-scale particles may present such unique properties that extrapolating from other types of studies may introduce, and not resolve, uncertainty. Some screening-level health effects studies conducted specifically on engineered nano-scale materials have been published and many more are underway. However, it is clear that the extent of research needed to fully and confidently understand the potential for health or environmental risk from engineered nano-scale particles may take years or even decades to complete. In spite of the great uncertainty, there is existing research and experience among researchers that can help to provide a taxonomy of particle properties, perhaps indicating a relative likelihood of risk, in order to prioritize nanoparticle risk research. To help structure this problem, a framework was developed from expert interviews of nanotechnology researchers. The analysis organizes the information as a system based on the risk assessment framework, in order to support the decision about safety. In the long term, this framework is designed to incorporate research results as they are generated, and therefore serve as a tool for estimating the potential for human health and environmental risk.     

应用框架图概述人体生理功能调节理论

以心血管活动和肺通气功能为例,对其生理功能调节的理论应用框架结构图进行了有机的联系和概括总结,框架图条理清楚、简单明了,便于学生学习和掌握,人体其它系统生理功能的调节,也可套用此框架图进行学习和理解。     

A study on the least squares estimator of multivariate isotonic regression function

Consider the problem of pointwise estimation of f in a multivariate isotonic regression model Z=f(X₁,…,X_d)+ϵ, where Z is the response variable, f is an unknown nonparametric regression function, which is isotonic with respect to each component, and ϵ is the error term. In this article, we investigate the behavior of the least squares estimator of f. We generalize the greatest convex minorant characterization of isotonic regression estimator for the multivariate case and use it to establish the asymptotic distribution of properly normalized version of the estimator. Moreover, we test whether the multivariate isotonic regression function at a fixed point is larger (or smaller) than a specified value or not based on this estimator, and the consistency of the test is established. The practicability of the estimator and the test are shown on simulated and real data as well.     

Enhancement of sigma level in the manufacturing of furnace nozzle through DMAIC approach of Six Sigma: a case study

In this paper, a case study on implementing Define, Measure, Analyze, Improve and Control (DMAIC) phases of Six Sigma programme in a furnace manufacturing company is reported. When Six Sigma was developed at Motorola, it was encapsulated with DMAIC and belt-based training infrastructure. Since belt-based training is expensive, companies with less revenue have been implementing only DMAIC phases. In this background, the impact of implementing DMAIC phases was examined in the research narrated in this paper through the reporting of the case study mentioned above. As the result of implementing DMAIC phases, the sigma level increased from 3.31 to 3.67 in the case of drilling a hole in a component called ‘furnace nozzle’. This increase in sigma level proved that DMAIC phases are powerful enough to enable the companies with less revenue to perform at six sigma level quality and acquire competitive strength.     

Path analysis and determining the distribution of indirect effects via simulation

The difference between a path analysis and the other multivariate analyses is that the path analysis has the ability to compute the indirect effects apart from the direct effects. The aim of this study is to investigate the distribution of indirect effects that is one of the components of path analysis via generated data. To realize this, a simulation study has been conducted with four different sample sizes, three different numbers of explanatory variables and with three different correlation matrices. A replication of 1000 has been applied for every single combination. According to the results obtained, it is found that irrespective of the sample size path coefficients tend to be stable. Moreover, path coefficients are not affected by correlation types either. Since the replication number is 1000, which is fairly large, the indirect effects from the path models have been treated as normal and their confidence intervals have been presented as well. It is also found that the path analysis should not be used with three explanatory variables. We think that this study would help scientists who are working in both natural and social sciences to determine sample size and different number of variables in the path analysis.     

初等表示的权的标积

半单李代数的素根可以用适当的初等表示的权来表示,反过来,初等表示的权也可以用素根来表示。在适当地选取了半单李代数的根系之后,就可算出初等表示权的标积。本文利用Cartan矩阵给出了一种计算半单李代数初等表示的权的标积的方法,并由此算出了二次Casimir算符的本征值。     

微波管雷基图等值线绘制技术

在文献[3]的基础上从数据处理方法上着手改进,采用逼近程度好,外推能力和唯一性强的趋势面残差叠加法进行数据的网格化,进而采用等值线追踪方法进行线性插值,从而绘制出较满意的雷基图,并使测绘时间缩短为原有的三分之一左右。     

二元判决图变量排序新方法

从遗传算法入手,利用已有的几种启发式变量排序方法的结果作为最初的染色体群体,并适当加入随机变量顺序,然后按照遗传算法的方法进行运算,经过多代循环找到近似最优解。实验结果表明,该方法比已有的启发式方法更有效,能够在全局范围内搜索最优解,对BDD的变量编序和遗传算法的运用具有参考价值。