Invariant co-ordinate selection

Summary.  A general method for exploring multivariate data by comparing different estimates of multivariate scatter is presented. The method is based on the eigenvalue–eigenvector decomposition of one scatter matrix relative to another. In particular, it is shown that the eigenvectors can be used to generate an affine invariant co-ordinate system for the multivariate data. Consequently, we view this method as a method for invariant co-ordinate selection . By plotting the data with respect to this new invariant co-ordinate system, various data structures can be revealed. For example, under certain independent components models, it is shown that the invariant co- ordinates correspond to the independent components. Another example pertains to mixtures of elliptical distributions. In this case, it is shown that a subset of the invariant co-ordinates corresponds to Fisher's linear discriminant subspace, even though the class identifications of the data points are unknown. Some illustrative examples are given.     

Contrasting strategies for tree species to cope with heat and dry conditions at urban sites

Street trees planted at tree pits with impermeable pavements are exposed to a high level of both, atmospheric and edaphic stress. For many species tree physiology, optimal growth, and consequently long-term vitality may be hampered under these harsh conditions. Therefore, maintaining the vitality and promoting the ecosystem services provided by urban trees, for example aesthetic values and microclimatic benefits, it is important to establish trees with a high tolerance to stressful urban environments. Measurements of leaf gas exchange, leaf water potential, leaf surface temperature and chlorophyll-fluorescence were used for identification of specific response of Corylus corluna L., Ginkgo biloba L., Liriodendron tulipifera L., and Tilia cordata Mill. ‘Greenspire’. The summer months in 2013 with a period of heat and drought over eight weeks only interrupted by two rainy days were appropriate to access tree’s strategies to cope with low water availability. During the measurement period, the influence of high temperatures, high values of vapor pressure deficit (VPD) and low soil water availability on stomatal conductance, water-use efficiency (WUE) and leaf water potential (Ψmin, Ψmax ) was highest for Liriodendron followed by Ginkgo. These species showed high reductions in WUE in case of higher air temperatures and high values of VPD. Results indicate an avoidance strategy under increasing heat and VPD. In contrast, Corylus and Tilia followed a tolerance strategy indicated by decreasing values of Ψmin and lower reductions of WUE. In conclusion, wide species-specific variation in response to high temperatures and high VPD indicates that substantial potential exists in the selection for dry and hot urban places.     

Career Engagement: Investigating Intraindividual Predictors of Weekly Fluctuations in Proactive Career Behaviors

This study applied a microlevel perspective on how within‐individual differences in motivational and social‐cognitive factors affected the weekly fluctuations of engagement in proactive career behaviors among a group of 67 German university students. Career self‐efficacy beliefs, perceived career barriers, experienced social career support, positive and negative emotions, and career engagement were assessed weekly for 13 consecutive weeks. Hierarchical linear regression analyses showed that above average levels of career engagement within individuals were predicted by higher than average perceived social support and positive emotions during a given week. Conversely, within‐individual differences in self‐efficacy, barriers, and negative emotions had no effect. The results suggest that career interventions should provide boosts in social support and positive emotions.     

Modified Wald statistics for generalized linear models

Summary: Wald statistics in generalized linear models are asymptotically ² distributed. The asymptotic chi–squared law of the corresponding quadratic form shows disadvantages with respect to the approximation of the finite–sample distribution. It is shown by means of a comprehensive simulation study that improvements can be achieved by applying simple finite–sample size approximations to the distribution of the quadratic form in generalized linear models. These approximations are based on a ² distribution with an estimated degree of freedom that generalizes an approach by Patnaik and Pearson. Simulation studies confirm that nominal level is maintained with higher accuracy compared to the Wald statistics.     

Occupational stress as it relates to higher education,individuals and organizations

This study examined through survey research methodology the degree to which, faculty, administrators and program coordinators, working in higher education, experience stress at work. The Occupational Stress Indicator was used, composed of four compound factors: sources of occupational stress, individual characteristics, coping strategies and the effects of stress. Preliminary findings showed that occupational stress has a negative impact on the degree of satisfaction with their achievement, value and growth, being strongest with faculty and coordinators, (dissatisfaction with career opportunities, personal growth, skill utilization). Another significant outcome was the dissatisfaction of faculty with the organizational design, structure and processes (communication, change implementation, motivation, supervision style, participation in decision-making). All possess individual characteristics of the Type A Scale; they all considered major sources of pressure in their jobs to be their relationships with others, home/work interface, their need to achieve personal and corporate success. Occupational stress has affected their state of health.     

Auswirkungen von Downsizing-Maßnahmen auf das organisationale Commitment der verbleibenden Mitarbeiter: Ein Vorher-Nachher-Vergleich

This study examines the consequences of downsizing efforts on organizational commitment, job satisfaction and work motivation of the remaining workforce (?survivors“) in a middle-sized telecommunication company. Employees were surveyed five months prior to the downsizing process (n=150) and eleven months thereafter (n=160). The assessment of organizational commitment was based on a questionnaire that was developed by Allen and Meyer (1990) within the scope of their three-components-model which includes affective, continuous and normative commitment. Although layoffs — as one part of the whole downsizing process — were not implemented in the investigated company, but only in a sister enterprise, which is part of the same holding, the affective commitment of employees towards their corporation dropped. On the other hand, the normative and the balanced commitment remained constant. Moreover, every second survivor showed reduced job satisfaction and work motivation. It should be noted that although the results of reorganisation and restructuring did not directly affect the employees of the investigated company, the emotional linkage between employees and employer was affected in a negative way. Additional findings from qualitative interviews suggest that restructuring was perceived to cause a crack in the prevailing corporate culture and the psychological contract. In addition, a deterioration of work conditions through work overload resulted.     

Corporate Social Responsibility als Integrationsherausforderung

The increasing debate on Corporate Social Responsibility (CSR) in science as well as in practice reflects the relevance of ethical questions for management. However, it is still unclear which responsibilities can be ascribed to corporations and how they can deal with such attributions on an operational level. The blurring and ambivalence in the discussion about CSR indicate a need for a theoretical clarification which is traced back to a not yet satisfactorily resolved integration of the constructs “profits” and “ethics”. The aim of the article is to provide a theoretical structure which is tailored to offer reliable focal points for a sophisticated handling of conflicts between profits and ethics.