Does sequential augmenting of simple linear heteroscedastic regression reduce variances of ordinary least-squares estimators?

If uncorrelated random variables have a common expected value and decreasing variances, then the variance of a sample mean is decreasing with the number of observations. Unfortunately, this natural and desirable variance reduction property (VRP) by augmenting data is not automatically inherited by ordinary least-squares (OLS) estimators of parameters. We derive a new decomposition for updating the covariance matrices of the OLS which implies conditions for the OLS to have the VRP. In particular, in the case of a straight-line regression, we show that the OLS estimators of intercept and slope have the VRP if the values of the explanatory variable are increasing. This also holds true for alternating two-point experimental designs.     

Comparison of Efficiency of Stratified and Unequal Probability Sampling

In this article, a choice of the optimum sampling design to study a finite population is studied. Three sampling schemes are compared, viz., Sunter's procedure of unequal probability sampling, stratified sampling under optimum stratification, and simple random sampling without replacement. The comparison is made against a background of various correlation between stratification and survey variables and various variability in the variables. Under weak correlation and large variability, stratification appeared to be more efficient than Sunter's procedure. Under strong correlation and/or low variability in the variables, the latter procedure was the most efficient. Simple random sampling was usually the least efficient.     

计算机辅助工程在建筑设备研究所的应用

本文讨论了建筑设备研究所在计算机辅助工程研究中的一些问题,70年代中期该研究所就开始用计算机设计机器及其部件,后来研究所购买了一些相关软件同时也开发了自己的设计软件并在液压起重机和其它建筑机械的设计计算中得到了应用。70-80年代计算机主要用于压力的分析与测量,机械的振动与稳定性分析,研究所从事机械设计、计算机数据库安全性研究及生态学、工效学方面的研究。在此也感谢其它国家的学者在计算机应用方面的交流与合作。     

Bounded leadership: An empirical study of leadership competencies,constraints, and effectiveness

Contrary to the previous leadership theories, which focus on specific and narrow aspects of leadership such as employee characteristics, leader’s authenticity, or boundary spanning, the bounded leadership theory is a broad and complex concept. It takes simultaneously many constraints, which are related to activities on an individual, team, organization, and stakeholder level. This study applies the bounded leadership theory to analyze the leadership constraints as the mediator of the relationship between leadership competencies and effectiveness. Our findings show that leaders’ competencies are not enough for them to be effective. Specific competencies enable leaders to overcome the set of constraints and then to increase their effectiveness.     

The educational orientation of participants in postgraduate managerial study programmes in Poland

The health care industry in Taiwan has faced many challenges in recent years. To tackle those challenges, many hospitals in Taiwan began using management techniques used in other industries. As a result, quality management has become important within Taiwan's health care industry. This study provides a perspective on how this health care industry, by developing both quality control circle (QCC) practices and organizational learning techniques, responded to those challenges. In this study, the authors conducted a comprehensive review of studies published between 1995 and 2007 in Taiwan. The review focused on the quality management, QCC, organizational learning and health care organization aspects reported in previous studies. The authors applied the 4Is (intuiting, interpreting, integrating and institutionalizing) conceptual framework of Crossan et al. (1999 Crossan, M. M., Lane, H. W. and White, R. E. 1999. An organizational learning framework: From intuition to institution. Academy of Management Review, 24(3): 522–537. [Crossref], [Web of Science ®] , [Google Scholar]) (Crossan, M.M., H.W. Lane, and R.E. White. 1999 Crossan, M. M., Lane, H. W. and White, R. E. 1999. An organizational learning framework: From intuition to institution. Academy of Management Review, 24(3): 522–537. [Crossref], [Web of Science ®] , [Google Scholar]. An organizational learning framework: From intuition to institution. Academy of Management Review 24, no. 3: 522–37). in their discussion of the linkage between quality improvement activities and organizational learning. The results revealed the existence of a link between organizational learning and QCC activities. In addition, the reviewed QCC activities facilitated organizational learning and contributed to health care quality improvements in the studied hospitals. Finally, QCC practices in hospitals facilitated dissemination of organizational learning concepts in those hospitals.     

The role of multi-objective optimization in negotiation and mediation support

The paper reviews the methodology of multi-objective modeling and optimization used in decision support based on computerized analytical models (as opposed to logical models used in expert systems) that represent expert knowledge in a given field. The essential aspects of this methodology relate to its flexibility: modeling and optimization methods are treated not as goals in themselves but as tools that help a sovereign user (an analyst or a decision maker) to interact with the model, to generate and analyze various decision options, to learn about possible outcomes of these decisions. Although the applications of such methods in negotiation and mediation support is scarce yet, their flexibility increases essentially the chances of such applications. Various aspects of negotiation and mediation methods related to multi-objective optimization and game theory are also reviewed. A possible application of the MCBARG system for supporting negotiation related to the acid rain problem is briefly summarized.     

Patterns of plant invasions at small spatial scale correspond with that at the whole country scale

Urban Ecosystems - Invasions were studied at different spatial scales, however these scales were rarely compared. The aim of this study is to compare the rate of expansion of eight alien plant...     

Frontiers of Stochastically Nondominated Portfolios

We consider the problem of constructing a portfolio of finitely many assets whose returns are described by a discrete joint distribution.We propose mean‐risk models that are solvable by linear programming and generate portfolios whose returns are nondominated in the sense of second‐order stochastic dominance. Next, we develop a specialized parametric method for recovering the entire mean‐risk efficient frontiers of these models and we illustrate its operation on a large data set involving thousands of assets and realizations.