A Novel Collinearity-Influential Observation Diagnostic Measure Based on a Group Deletion Approach

High leverage points can induce or disrupt multicollinearity patterns in data. Observations responsible for this problem are generally known as collinearity-influential observations. A significant amount of published work on the identification of collinearity-influential observations exists; however, we show in this article that all commonly used detection techniques display greatly reduced sensitivity in the presence of multiple high leverage collinearity-influential observations. We propose a new measure based on a diagnostic robust group deletion approach. Some practical cutoff points for existing and developed diagnostics measures are also introduced. Numerical examples and simulation results show that the proposed measure provides significant improvement over the existing measures.     

Bounding the total domination subdivision number of a graph in terms of its order

The total domination subdivision number \(\mathrm{sd}_{\gamma _{t}}(G)\) of a graph G is the minimum number of edges that must be subdivided (each edge in G can be subdivided at most once) in order to increase the total domination number. In this paper we prove that \(\mathrm{sd}_{\gamma_{t}}(G)\leq \lfloor\frac{2n}{3}\rfloor\) for any simple connected graph G of order n≥3 other than K ₄. We also determine all simple connected graphs G with \(\mathrm{sd}_{\gamma_{t}}(G)=\lfloor\frac{2n}{3}\rfloor\).     

Competencies of disabled entrepreneurs in Iran: implications for learning and development

This qualitative research set out to explore competencies of disabled entrepreneurs by presenting their lived experiences in developing their capabilities to create and manage their own business. The research also aimed to identify the dimensions and components of entrepreneurial competencies of disabled entrepreneurs. The participants were 16 entrepreneurs with physical and mobility disabilities, four educational managers of disabled vocational education and rehabilitation centers, and four entrepreneurship academics. Our findings suggested that the disabled entrepreneurs possess specific personal and functional entrepreneurial competencies. Personal competencies include attitudinal competencies, entrepreneurial self-efficacy and entrepreneurship learning self-efficacy. Functional competencies encompass entrepreneurial competencies, commitment and social competencies.     

Transport Mode Selection for Toxic Gases: Rail or Road?

A significant majority of hazardous materials (hazmat) shipments are moved via the highway and railroad networks, wherein the latter mode is generally preferred for long distances. Although the characteristics of highway transportation make trucks the most dominant surface transportation mode, should it be preferred for hazmat whose accidental release can cause catastrophic consequences? We answer this question by first developing a novel and comprehensive assessment methodology—which incorporates the sequence of events leading to hazmat release from the derailed railcars and the resulting consequence—to measure rail transport risk, and second making use of the proposed assessment methodology to analyze hazmat transport risk resulting from meeting the demand for chlorine and ammonia in six distinct corridors in North America. We demonstrate that rail transport will reduce risk, irrespective of the risk measure and the transport corridor, and that every attempt must be made to use railroads to transport these shipments.     

Efficient Estimation of the PDF and the CDF of the Exponentiated Gumbel Distribution

The exponentiated Gumbel model has been shown to be useful in climate modeling including global warming problem, flood frequency analysis, offshore modeling, rainfall modeling, and wind speed modeling. Here, we consider estimation of the probability density function (PDF) and the cumulative distribution function (CDF) of the exponentiated Gumbel distribution. The following estimators are considered: uniformly minimum variance unbiased (UMVU) estimator, maximum likelihood (ML) estimator, percentile (PC) estimator, least-square (LS) estimator, and weighted least-square (WLS) estimator. Analytical expressions are derived for the bias and the mean squared error. Simulation studies and real data applications show that the ML estimator performs better than others.     

Internationalization Orientation in SMEs: The Mediating Role of Technological Innovation

This study examines the relationship between internationalization orientation and international performance of small and medium-sized enterprises (SMEs), and the mediating effect of technological innovation. Prior research suggests that internationalization is a prominent strategic choice for SMEs growth and profitability. However, there is still no explicit agreement on how internationalization affects international performance. Similarly, the role of innovation on performance has long been emphasized, but the implications of technological innovation on international performance are still eluding us. Our investigation of 116 SMEs in the United Kingdom reveals that internationalization orientation has a significant effect on their international performance, with SMEs adopting simultaneously an inward and outward international orientation achieving superior results. We further demonstrate that there is an inverted U-shaped relationship between technological innovation and international firm performance among SMEs. Meanwhile, we find that technological innovation positively mediates the effect of internationalization orientation on international firm performance, particularly for the SMEs exhibiting moderate levels of technological innovation activities. The findings of this study suggest that managers can improve international performance by combining inward and outward internationalization orientation with technological innovation activities in their strategic decisions.     

Cross‐Cultural Measurement Invariance of Adolescent Self‐Report on the Pediatric Quality of Life Inventory™ 4.0

This study evaluated the cross‐cultural measurement invariance of the Pediatric Quality of Life Inventory version 4.0 (PedsQL^?) among adolescents sampled from Bulgaria, Croatia, India, Indonesia, Nigeria, Serbia, and Turkey. The multiple‐indicator multiple‐cause (MIMIC) model was used, which allowed controlling of demographic variables (i.e., age, gender, and socioeconomic status). Significant effects of country on scores within the PedsQL^? domains were observed, with up to 17 items showing differential item functioning (DIF) across the countries. We did not find support for cross‐cultural measurement invariance hypotheses for scores on the PedsQL^? adolescent self‐report in this study. Researchers should use caution in making cross‐cultural quality of life comparisons while using the PedsQL.     

Promoting positive development among refugee adolescents

Of the estimated 35.3 million refugees around the world (UNHCR, Figures at a Glance, 2022), approximately 50% are children under the age of 18. Refugee adolescents represent a unique group as they navigate developmental tasks in an unstable and often threatening environment or in resettlement contexts in which they often face marginalization. In addition to physiological, social, and psychological changes that mark adolescence, refugee youth often face traumatic experiences, acculturative stress, discrimination, and a lack of basic resources. In this consensus statement, we examine research on refugee adolescents' developmental tasks, acculturative tasks, and psychological adjustment using Suárez-Orozco and colleague's integrative risk and resilience model for immigrant-origin children and youth proposed by Suárez-Orozco et al. Finally, we discuss recommendations—moving from proximal to more distal contexts.