A framework for understanding collective leadership: The selective utilization of leader and team expertise within networks

To date, the dominant approach to leadership research assumes that all aspects of the leadership role within a team are embodied by a single individual. In the real world, however, this is rarely the case. Rather, multiple individuals within the team may serve as leaders in both formal and informal capacities, and the shifting of leadership responsibilities is often rooted in which individual's expertise is most relevant to the given problem. In the present effort, we add to the rapidly growing body of work that focuses on the distribution of the leadership role among multiple individuals. We have reviewed relevant extant literature and proposed an integrated framework for understanding the collective leadership process. Also, in developing this framework we have taken an information and expertise-based approach such that we propose that collective leadership, or the distribution of the leadership role, is a function of selectively utilizing the information or specialized expertise that individuals within the network possess. In reviewing the framework, 55 propositions with regard to the collective leadership process are outlined and suggestions for future research are provided.     

Wildfire Risk Transmission in the Colorado Front Range,USA

Wildfires are a global phenomenon that in some circumstances can result in human casualties, economic loss, and ecosystem service degradation. In this article we spatially identify wildfire risk transmission pathways and locate the areas of highest exposure of human populations to wildland fires under severe, but not uncommon, weather events. We quantify varying levels of exposure in terms of population potentially affected and tie the exposure back to the spatial source of the risk for the Front Range of Colorado, USA. We use probabilistic fire simulation modeling to address where fire ignitions are most likely to cause the highest impact to human communities, and to explore the role that various landowners play in that transmission of risk. Our results indicated that, given an ignition and the right fire weather conditions, large areas along the Front Range in Colorado could be exposed to wildfires with high potential to impact human populations, and that overall private ignitions have the potential to impact more people than federal ignitions. These results can be used to identify high‐priority areas for wildfire risk mitigation using various mitigation tools.     

ALCOHOL, ETHNICITY, AND VIOLENCE: The Role of Alcohol Availability for Latino and Black Aggravated Assaults and Robberies

This article is one of the first to assess the impact of alcohol availability, an important but understudied neighborhood element, and other social disorganization measures for Latino and black aggravated assault and robbery victimizations. Using data from Miami, Florida, for 1996 and 1997, we find that although most predictors have similar effects on the outcomes for both groups, higher alcohol availability rates are associated with more Latino but not black victims. To explain this finding, we relate the criminogenic influence of alcohol to contextual features of Latino and black neighborhoods, thereby integrating qualitative observations and quantitative data. Higher concentrations of recent immigrants are also related to fewer black assault victims, more Latino assault victims, but not to robberies for either group.     

Why a universal population‐level approach to the prevention of child abuse is essential

This paper argues for the importance of adopting a population‐level approach to promote more effective parenting and to reduce the risk of child maltreatment. Family‐based interventions based on social learning principles have been shown to make a useful contribution in the treatment of child maltreatment. However, typically such programmes have been used to treat parents who have already become involved in the child protection system. We argue that the creation of community‐wide support structures to support positive parenting is needed to reduce the prevalence of child maltreatment. Such an approach requires several criteria to be met. These include having knowledge about the prevalence rates for the targeted child outcomes sought, knowledge about the prevalence of various parenting and family risk factors, evidence that changing family risk factors reduces the prevalence of targeted problems, having culturally appropriate, cost‐effective, evidence‐based interventions available and making these widely accessible. Copyright © 2003 John Wiley & Sons, Ltd.     

Estimation in Semiparametric Marginal Shared Gamma Frailty Models

The semiparametric marginal shared frailty models in survival analysis have the non–parametric hazard functions multiplied by a random frailty in each cluster, and the survival times conditional on frailties are assumed to be independent. In addition, the marginal hazard functions have the same form as in the usual Cox proportional hazard models. In this paper, an approach based on maximum likelihood and expectation–maximization is applied to semiparametric marginal shared gamma frailty models, where the frailties are assumed to be gamma distributed with mean 1 and variance θ. The estimates of the fixed–effect parameters and their standard errors obtained using this approach are compared in terms of both bias and efficiency with those obtained using the extended marginal approach. Similarly, the standard errors of our frailty variance estimates are found to compare favourably with those obtained using other methods. The asymptotic distribution of the frailty variance estimates is shown to be a 50–50 mixture of a point mass at zero and a truncated normal random variable on the positive axis for θ₀ = 0. Simulations demonstrate that, for θ₀ < 0, it is approximately an x −(100 − x )%, 0 ≤ x ≤ 50, mixture between a point mass at zero and a truncated normal random variable on the positive axis for small samples and small values of θ₀; otherwise, it is approximately normal.     

Using number of failed contact attempts to adjust for non-ignorable non-response

Summary.  We present a general method of adjustment for non-ignorable non-response in studies where one or more further attempts are made to contact initial non-responders. A logistic regression model relates the probability of response at each contact attempt to covariates and outcomes of interest. We assume that the effect of these covariates and outcomes on the probability of response is the same at all contact attempts. Knowledge of the number of contact attempts enables estimation of the model by using only information from the respondents and the number of non-responders. Three approaches for fitting the response models and estimating parameters of substantive interest and their standard errors are compared: a modified conditional likelihood method in which the fitted inverse probabilities of response are used in weighted analyses for the outcomes of interest, an EM procedure with the Louis formula and a Bayesian approach using Markov chain Monte Carlo methods. We further propose the creation of several sets of weights to incorporate uncertainty in the probability weights in subsequent analyses. Our methods are applied as a sensitivity analysis to a postal survey of symptoms in Persian Gulf War veterans and other servicemen.     

Modeling Fear of Crime and Perceived Victimization Risk: The (In)Significance of Neighborhood Integration

The bulk of fear–of–crime research has been limited to one questionnaire item that asks respondents to assess their personal safety by answering "how safe they feel alone in their neighborhoods at night." More recently, however, studies have pointed to the multidimensional nature of fear of crime and perceived risk of victimization. Following this line of inquiry, we investigate the potential impact of several variable sets on three measures of fear of crime or risk perception—the traditional risk assessment of being alone at night, a measure of worry about crime, and a more general assessment of neighborhood safety. Of particular interest are the relative effects of neighborhood integration variables on the measures of fear/risk. A comparison of the effects of neighborhood integration variables with a set of perceived neighborhood disorder, routine activities, socio–demographic characteristics, and victimization experience variables reveals that the neighborhood disorder (incivilities), income, and crime prevention measures produce the most consistently significant effects on fear of crime and perceived risk. Contrary to our expectations, neighborhood integration variables appear to be relatively unimportant.     

Review essay — administrative delay at the NLRB: Some modest proposals

V. Conclusion The latest edition of Miller’s Appraisal provides an updated glimpse into the inner workings of the NLRB. Miller’s observations are knowledgeable and understandable, and his book is an important contribution for academics, the labor bar, and the Board itself. We hope it spurs further study of the Board’s administration of the Act and exploration of ways to improve it. Miller’s pessimism about potential reforms, short of his proposed abolition of the five-member Board in favor of a new labor and employment division of the federal district courts, goes too far. We have suggested a few changes that would make the Board more efficient without affecting the Board’s substantive mission. Hopefully, with further efforts like Miller’s in the future, the Board will effect a consistent improvement upon its somewhat spotty record of efficiency and will keep the NLRA vibrant well into this new century. We especially thank former NLRB Regional Director Daniel Silverman for his invaluable contributions to this article.