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71.
Relative income differences are likely to lead to envy within a reference group. Envy in turn influences social behavior and individual performance. While positional concerns are apparent in daily life, empirical evidence is rare in the economic literature. This paper investigates the impact of the relative income position on individuals’ performance or productivity. As ?performance“ is difficult to measure we turn to soccer players whose performance has been well documented. The broad sample covers eight seasons of the German premier soccer league (Bundesliga) between 1995 and 2004, and includes 1040 players, a salary proxy and several performance variables. The results show that player performance is strongly affected by relative income position. A disadvantage in the relative income position reduces productivity. The larger the income differences within a team, the stronger are the effects of positional concern. Team composition also significantly affects behaviour.  相似文献   
72.
Information and communication technologies (IT) permeate both the business and the private world. They cause profound changes for companies in terms of structure, leadership, culture, education and the position of individuals within the context of the company. Established structures, decision making habits and methods of communication are being called into question. This means that communication is neither explicitly controllable nor in some cases even specified, but it also should not be viewed as arbitrary. Structures which are treated as contingent require meta-management, reflection and determination. Leaders are forced to act within a constellation of tensions between the reduction and the expansion of complexity as basic functions of structuring. Ideally this type of steering takes place consciously and with a view toward the future, taking into account the increasing complexity and dynamics of the environment and the corporate culture. Empirical studies of our four intervention research projects show that the situation for many companies is sobering. Companies cannot always entirely interpret the rapid development of communication technologies and the consequences it brings with it, nor can they completely make use of its potential advantages. Companies and individuals are forced to think actively within the networked economy. The demand for further education shifts between the company (expertise, employee loyalty) on the one hand and the responsibility of the individual for his or her own development on the other. Agreements are the key to bringing harmony and new solutions to the conflicts among the differing interests of individuals, subsystems and the company as a whole. Considering the complex requirements for companies and management caused by IT, this article shows that reflective observation of intervention research, guided by theory and with a focus on targeted change of management practice, is a process which provides new opportunities for action in both theory and practice. In this process, focusing (systemization) and reflection (enhancement of perspectives) are fundamental keys for dealing with complexity.  相似文献   
73.
Some of the rapid recent growth in disability income receipt in the United States is attributable to single mothers post-welfare reform. Yet, we know little about how disability benefit receipt affects the economic well-being of single mother families, or how unsuccessful disability applicants fare. We compare disability recipients to unsuccessful applicants and those who never applied among current and former welfare recipients, and examine how application and receipt affect material hardships and subjective measures of well-being. We then examine whether alternative ways of making ends meet mediate differences in well-being. After controlling for alternative sources of support, no significant differences in overall actual hardships or difficulty living on current income remained between the three groups. However, even after controlling for these strategies, unsuccessful applicants were significantly more likely to report that they expected hardships in the next two months. Our results suggest a pervasive level of economic insecurity among unsuccessful applicants.  相似文献   
74.
    
Source localization, such as detecting a nuclear source in an urban area or ascertaining the origin of a chemical plume, is generally regarded as a well‐documented inverse problem; however, optimally placing sensors to collect data for such problems is a more challenging task. In particular, optimal sensor placement—that is, measurement locations resulting in the least uncertainty in the estimated source parameters—depends on the location of the source, which is typically unknown a priori. Mobile sensors are advantageous because they have the flexibility to adapt to any given source position. While most mobile sensor strategies designate a trajectory for sensor movement, we instead employ mutual information, based on Shannon entropy, to choose the next measurement location from a discrete set of design conditions.  相似文献   
75.
    
This study explored how the U.S. Departments of Housing and Urban Development-Veterans Affairs Supportive Housing (HUD-VASH) program applies Housing First principles in the context of ten single-site programs. Focus group discussions with 64 HUD-VASH staff and community partners explored how the programs were influenced by Housing First principles and specific strategies to implement these principles in a single-site setting. Focus group respondents described resourceful ways that the principles of Housing First were implemented in their programs specifically related to (1) housing choice and structure, (2) separation of housing and services, (3) service philosophy, and (4) service array. Several of the Housing First domains cite the importance of integrated housing and the provision of services off-site; it was of particular interest to learn how single-site programs address these issues logistically. Lessons learned from this study include the importance of leveraging the independent yet overlapping tasks of case management and property management to ensure functional – if not geographic – separation of housing and services; maintaining staff on-site to address Veterans’ needs; working with community service organizations to complement the array of service available to residents; and housing single-site programs in mixed-use buildings.  相似文献   
76.
    
The current study examined the role of hypothalamic‐pituitary‐adrenal reactivity (a physiological indicator of stress) in early infancy as a mediator of the relationship between maternal postpartum depression and toddler behavior problems. Participants were 137 at‐risk mothers and their children participating in a longitudinal study of intergenerational transmission of risk. Mothers’ depression was measured five times during the infants’ first 18 months. Infant cortisol was collected during a social stressor (the still‐face paradigm) when infants were 6 months old, and mothers reported on toddlers’ internalizing and externalizing symptoms at 18 months. Among this sample of high‐risk mother–infant dyads, early postpartum depression predicted atypical infant cortisol reactivity at 6 months, which mediated the effect of maternal depression on increased toddler behavior problems. Clinical implications are discussed.  相似文献   
77.
    
We investigate the problem of estimating geodesic tortuosity and constrictivity as two structural characteristics of stationary random closed sets. They are of central importance for the analysis of effective transport properties in porous or composite materials. Loosely speaking, geodesic tortuosity measures the windedness of paths, whereas the notion of constrictivity captures the appearance of bottlenecks resulting from narrow passages within a given materials phase. We first provide mathematically precise definitions of these quantities and introduce appropriate estimators. Then, we show strong consistency of these estimators for unboundedly growing sampling windows. In order to apply our estimators to real data sets, the extent of edge effects needs to be controlled. This is illustrated using a model for a multiphase material that is incorporated in solid oxide fuel cells.  相似文献   
78.
    
Meta‐analyses based on systematic literature reviews are commonly used to obtain a quantitative summary of the available evidence on a given topic. However, the reliability of any meta‐analysis is constrained by that of its constituent studies. One major limitation is the possibility of small‐study effects, when estimates from smaller and larger studies differ systematically. Small‐study effects may result from reporting biases (ie, publication bias), from inadequacies of the included studies that are related to study size, or from reasons unrelated to bias. We propose two estimators based on the median and mode to increase the reliability of findings in a meta‐analysis by mitigating the influence of small‐study effects. By re‐examining data from published meta‐analyses and by conducting a simulation study, we show that these estimators offer robustness to a range of plausible bias mechanisms, without making explicit modelling assumptions. They are also robust to outlying studies without explicitly removing such studies from the analysis. When meta‐analyses are suspected to be at risk of bias because of small‐study effects, we recommend reporting the mean, median and modal pooled estimates.  相似文献   
79.
    
In the quest to model various phenomena, the foundational importance of parameter identifiability to sound statistical modeling may be less well appreciated than goodness of fit. Identifiability concerns the quality of objective information in data to facilitate estimation of a parameter, while nonidentifiability means there are parameters in a model about which the data provide little or no information. In purely empirical models where parsimonious good fit is the chief concern, nonidentifiability (or parameter redundancy) implies overparameterization of the model. In contrast, nonidentifiability implies underinformativeness of available data in mechanistically derived models where parameters are interpreted as having strong practical meaning. This study explores illustrative examples of structural nonidentifiability and its implications using mechanistically derived models (for repeated presence/absence analyses and dose–response of Escherichia coli O157:H7 and norovirus) drawn from quantitative microbial risk assessment. Following algebraic proof of nonidentifiability in these examples, profile likelihood analysis and Bayesian Markov Chain Monte Carlo with uniform priors are illustrated as tools to help detect model parameters that are not strongly identifiable. It is shown that identifiability should be considered during experimental design and ethics approval to ensure generated data can yield strong objective information about all mechanistic parameters of interest. When Bayesian methods are applied to a nonidentifiable model, the subjective prior effectively fabricates information about any parameters about which the data carry no objective information. Finally, structural nonidentifiability can lead to spurious models that fit data well but can yield severely flawed inferences and predictions when they are interpreted or used inappropriately.  相似文献   
80.
    
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