Identification of outlying height and weight data in the Iranian National Health Survey 1990-92

Data on the weights and heights of children 2-18 yeas old in Iran were obtained in a National Health Survey of 10 660 families in 1990-92. Data were 'cleaned' in 1 year age groups. After excluding gross outliers by inspection of bivariate scatter plots, Box-Cox power transformations were used to normalize the distributions of height and weight. If a multivariate Box-Cox power transformation to normality exists, then it is equivalent to normalizing the data variable by variable. After excluding gross outliers, exclusions based on the Mahalanobis distance were almost identical to those identified by Hadi's iterative procedure, because the percentages of outliers were small. In all, 1% of the observations were gross outliers and a further 0.4% were identified by multivariate analysis. Review of records showed that the outliers identified by multivariate analysis resulted from data-processing errors. After transformation and 'cleaning', the data quality was excellent and suitable for the construction of growth charts.     

A bayesian analysis of the mixed linear model

The mixed model is defined. The exact posterior distribution for the fixed effect vector is obtained. The exact posterior distribution for the error variance is obtained. The exact posterior mean and variance of a Bayesian estimator for the variances of random effects is also derived. All computations are non-iterative and avoid numerical integrations.     

The impact of in-vehicle cell-phone use on accidents or near-accidents among college students

With in-vehicle use of cell phones rapidly increasing, the safety of young drivers, who represent 14% of licensed drivers but 26% of drivers involved in fatal crashes, may be disproportionately threatened. The authors used a questionnaire to examine the association between in-vehicle cell-phone use and accidents or near-accidents among 1,291 conveniently recruited college students in 4 states. Of the 1,185 respondents who were drivers, 87% had a cell phone, and 86% of the cell-phone owners reported talking while driving at least occasionally. Of the 762 reported accidents or near-accidents, 21% (n = 159) involved at least 1 of the drivers talking while driving. Chi-square tests and logistic regression analyses showed that the frequency, not the duration, of drivers talking while driving was related to experiencing accidents or near-accidents. Differences between drivers who used cell phones and nonusers in unsafe driving behaviors and attitudes were also examined, and target groups for intervention efforts against talking on a cell phone while driving are suggested.     

Majorization and the spectral radius of starlike trees

A starlike tree is a tree with exactly one vertex of degree greater than two. The spectral radius of a graph G, that is denoted by \(\lambda (G)\), is the largest eigenvalue of G. Let k and \(n_1,\ldots ,n_k\) be some positive integers. Let \(T(n_1,\ldots ,n_k)\) be the tree T (T is a path or a starlike tree) such that T has a vertex v so that \(T{\setminus } v\) is the disjoint union of the paths \(P_{n_1-1},\ldots ,P_{n_k-1}\) where every neighbor of v in T has degree one or two. Let \(P=(p_1,\ldots ,p_k)\) and \(Q=(q_1,\ldots ,q_k)\), where \(p_1\ge \cdots \ge p_k\ge 1\) and \(q_1\ge \cdots \ge q_k\ge 1\) are integer. We say P majorizes Q and let \(P\succeq _M Q\), if for every j, \(1\le j\le k\), \(\sum _{i=1}^{j}p_i\ge \sum _{i=1}^{j}q_i\), with equality if \(j=k\). In this paper we show that if P majorizes Q, that is \((p_1,\ldots ,p_k)\succeq _M(q_1,\ldots ,q_k)\), then \(\lambda (T(q_1,\ldots ,q_k))\ge \lambda (T(p_1,\ldots ,p_k))\).     

Measuring Human,Physical and Structural Capital Efficiency Performance of Insurance Companies

Based on the strategy perspective of intellectual capital, this paper proposes an integrated framework that is practical to estimate the human, physical, and structural capitals (intellectual capital) efficiency performance, at firm level. This paper uses a dynamic network data envelopment analysis model to estimate the intellectual capital efficiency at three levels in the insurance industry over the period of 2005–2012. Within the insurance industry, deficiencies occurred in the human and structural capital stages as opposed to the physical capital stage. A further investigation indicates that total investment is the major concern for the deficiencies. Moreover, the cluster analysis highlights the strengths and weaknesses of the insurers based on their inherently similar efficiencies. Malaysian insurance industry need to translate and promote the existing knowledge-based economy agenda lauded by the government to improve the intellectual capital efficiency, particularly at the human capital level.     

Relationships between psychological capital,job satisfaction,and organizational commitment in the Saudi oil and petrochemical industries

During the past decade, Saudi Arabia experienced a significant social, economic, and organizational change. The rapid economic growth created a need for seasoned management professionals and necessitated the development of human capital. Psychological capital, a newly developed construct by academics and practitioners, is defined as the extent to which an individual operates in a positive psychological state, and this state is characterized by high self-efficacy, optimism, hope, and resiliency. By measuring the positive psychological constructs, an organization can learn about employees’ positive psychological states and how training and support can promote positive psychological states. Improving the positive psychological capital can lead to better organizational commitment, favorable organizational citizenship behaviors, lower employee absenteeism, and higher job satisfaction. This quantitative study examined the relationship among psychological capital, job satisfaction, and organizational commitment through a sample of managers in the Saudi Arabian oil and petrochemical industries.     

Monitoring two-stage processes with a profile at the second stage

In the multistage processes, quality of a process or a product at each stage is related to the previous stage(s). This property is referred to as a cascade property. Sometimes, quality of a process is characterized by a profile. In this paper, we consider a two-stage process with a normal quality characteristic in the first stage and a simple linear regression profile in the second stage. Then we propose two methods to monitor quality characteristics in both stages. The performance of the proposed two methods is evaluated through a numerical example in terms of average run length criterion.     

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.     

Equity Ownership in Cross‐border Mergers and Acquisitions by British Firms: An Analysis of Real Options and Transaction Cost Factors

The authors investigate the factors influencing the share of equity ownership sought in cross‐border mergers and acquisitions (CBM&As). Drawing on real options theory and transaction cost economics (TCE), they address and hypothesize key factors linked to commitment under exogenous uncertainty and the separation of desired and non‐desired assets’ influence on share of equity sought by acquiring firms in CBM&As. Empirical analysis based on 1872 CBM&As undertaken by British firms in both developed and emerging economies shows that British MNEs are more likely to pursue a partial acquisition in a target foreign firm when those foreign firms are from culturally distant countries. Further, findings support the view that the high cost of separating desired assets from non‐desired assets motivates firms to make a partial acquisition rather than acquire the target completely. This is one of the first studies to use real options theory to address the cost of commitment under exogenous uncertainty, as well as TCE logic to address the separation of desired and non‐desired assets in the target firm while analysing equity ownership sought in CBM&As. Empirically, this paper contributes by examining CBM&As by British firms in both developed and emerging markets.