More on the restricted Liu estimator in the logistic regression model

?iray et al. proposed a restricted Liu estimator to overcome multicollinearity in the logistic regression model. They also used a Monte Carlo simulation to study the properties of the restricted Liu estimator. However, they did not present the theoretical result about the mean squared error properties of the restricted estimator compared to MLE, restricted maximum likelihood estimator (RMLE) and Liu estimator. In this article, we compare the restricted Liu estimator with MLE, RMLE and Liu estimator in the mean squared error sense and we also present a method to choose a biasing parameter. Finally, a real data example and a Monte Carlo simulation are conducted to illustrate the benefits of the restricted Liu estimator.     

New Shrinkage Parameters for the Liu-type Logistic Estimators

The binary logistic regression is a widely used statistical method when the dependent variable has two categories. In most of the situations of logistic regression, independent variables are collinear which is called the multicollinearity problem. It is known that multicollinearity affects the variance of maximum likelihood estimator (MLE) negatively. Therefore, this article introduces new shrinkage parameters for the Liu-type estimators in the Liu (2003) in the logistic regression model defined by Huang (2012) in order to decrease the variance and overcome the problem of multicollinearity. A Monte Carlo study is designed to show the goodness of the proposed estimators over MLE in the sense of mean squared error (MSE) and mean absolute error (MAE). Moreover, a real data case is given to demonstrate the advantages of the new shrinkage parameters.     

An empirical investigation of managerial achievement,job statisfaction and values: An informational perspective

Provision of appropriate information and feedback to managers is crucial for the success of an organization. This study examines the availability and desirability of various informational feedback mechanisms to a group of managers in Saudi Arabia. Study results highlight some interesting differences among managers with varying value orientations and satisfaction profiles in terms of their informational needs. Implications of the findings are discussed.     

An improved and efficient biased estimation technique in logistic regression model

Abstract

In this article, we propose a new improved and efficient biased estimation method which is a modified restricted Liu-type estimator satisfying some sub-space linear restrictions in the binary logistic regression model. We study the properties of the new estimator under the mean squared error matrix criterion and our results show that under certain conditions the new estimator is superior to some other estimators. Moreover, a Monte Carlo simulation study is conducted to show the performance of the new estimator in the simulated mean squared error and predictive median squared errors sense. Finally, a real application is considered.     

Cultural values as determinants of executive attitudes on decision making: An empirical evaluation

This article presents an empirical, cross-cultural investigation of executive attitudes on decision making, risk taking, and executive courage. Twenty-nine Arab and 40 American executives participated in this study. Six hypotheses were tested, with the results showing significant differences between managers from the two business cultures. Recommendations and directions for future research are provided.     

Developing alliances between U.S. and Portuguese executives: The impact of executive courage

This study represents an effort to gain insights into the differences between U.S. and Portuguese executives with regard to their attitudes toward the role of executive courage in the business organization. Eighty Portuguese and 40 American executives participated in the study. Four research questions were formulated and investigated. Results show that the two groups of executives tended to be more similar than different. However, some statistically significant differences between the two samples were detected. Portuguese organizations exhibited significantly more control over the actions of their executives and rewarded efficiency rather than effectiveness, when compared to American business organizations. Implications for strategic alliances between Portuguese and American executives are discussed and recommendations for future research are provided.     

Some new methods to solve multicollinearity in logistic regression

The binary logistic regression is a widely used statistical method when the dependent variable is binary or dichotomous. In some of the situations of logistic regression, independent variables are collinear which leads to the problem of multicollinearity. It is known that multicollinearity affects the variance of maximum likelihood estimator (MLE) negatively. Thus, this article introduces new methods to estimate the shrinkage parameters of Liu-type logistic estimator proposed by Inan and Erdogan (2013 Inan, D., Erdogan, B. E. (2013). Liu-type logistic estimator. Communications in Statistics-Simulation and Computation 42(7):1578–1586. [Google Scholar]) which is a generalization of the Liu-type estimator defined by Liu (2003 Liu, K. (2003). Using Liu-type estimator to combat collinearity. Communications in Statistics: Theory and Methods 32(5):1009–1020. [Google Scholar]) for the linear model. A Monte Carlo study is used to show the effectiveness of the proposed methods over MLE using the mean squared error (MSE) and mean absolute error (MAE) criteria. A real data application is illustrated to show the benefits of new methods. According to the results of the simulation and application proposed methods have better performance than MLE.     

Restricted ridge estimator in the logistic regression model

It is known that when the multicollinearity exists in the logistic regression model, variance of maximum likelihood estimator is unstable. As a remedy, Schaefer et al. presented a ridge estimator in the logistic regression model. Making use of the ridge estimator, when some linear restrictions are also present, we introduce a restricted ridge estimator in the logistic regression model. Statistical properties of this newly defined estimator will be studied and comparisons are done in the simulation study in the sense of mean squared error criterion. A real-data example and a simulation study are introduced to discuss the performance of this estimator.     

An empirical investigation of motivation and effective performance: A comparison of Arab and U.S. cultures

This study empirically examines motivational profiles within the Arab culture and compares them with the U.S. culture. The associations of needs for achievement, affiliation, and power with effectiveness (salary, promotion, and GPA) and job satisfaction in the Arab culture are investigated. The need for affiliation is negatively associated with effectiveness for managers and students, and the need for power is positively associated with effectiveness for managers. The Arab culture exhibits higher affiliation need, while the U.S. culture exhibits higher power and achievement needs. However, the two cultures exhibit similar profiles of effective motivation for managers, students, and professionals.     

《突厥语大词典》等文献中的梵语借词

文章以历史上的文化接触为背景,对《突厥语大词典》等从公元8世纪到13世纪成书的古代维吾尔文献中的梵语借词进行了考证。