Introduction to stochastic actor-based models for network dynamics

Stochastic actor-based models are models for network dynamics that can represent a wide variety of influences on network change, and allow to estimate parameters expressing such influences, and test corresponding hypotheses. The nodes in the network represent social actors, and the collection of ties represents a social relation. The assumptions posit that the network evolves as a stochastic process ‘driven by the actors’, i.e., the model lends itself especially for representing theories about how actors change their outgoing ties. The probabilities of tie changes are in part endogenously determined, i.e., as a function of the current network structure itself, and in part exogenously, as a function of characteristics of the nodes (‘actor covariates’) and of characteristics of pairs of nodes (‘dyadic covariates’). In an extended form, stochastic actor-based models can be used to analyze longitudinal data on social networks jointly with changing attributes of the actors: dynamics of networks and behavior.     

Dynamic Pricing and Lead‐Time Policies for Make‐to‐Order Systems*

Make‐to‐order firms use different approaches for managing their lead‐times and pricing in the face of changing market conditions. A particular firm's approach may be largely dictated by environmental constraints. For example, it makes little sense to carefully manage lead‐time if its effect on demand is muted, as it can be in situations where leadtime is difficult for the market to gauge or requires investment to estimate. Similarly, it can be impractical to change capacity and price. However, environmental constraints are likely to become less of an issue in the future with the expanding e‐business infrastructure, and this trend raises questions into how to manage effectively the marketing mix of price and lead‐time in a more “friction‐free” setting. We study a simple model of a make‐to‐order firm, and we examine policies for adjusting price and capacity in response to periodic and unpredictable shifts in how the market values price and lead‐time. Our analysis suggests that maintaining a fixed capacity while using lead‐time and/or price to absorb changes in the market will be most attractive when stability in throughput and profit are highly valued, but in volatile markets, this stability comes at a cost of low profits. From a pure profit maximization perspective, it is best to strive for a short and consistent lead‐times by adjusting both capacity and price in response to market changes.     

The Challenge of Coordination in Central Government Organizations: The Norwegian Case

This paper addresses coordination problems in central government by focusing on the Norwegian case. The main research questions are: What are the experiences of civil servants concerning horizontal and vertical coordination, and internal and external coordination? What is the relative importance of structural, demographic and cultural variables for explaining variations in civil servants’ perception of coordination? The data base is a questionnaire to civil servants in ministries and central agencies in 2006. The main findings are that there are more problems with horizontal coordination than with vertical coordination; that coordination problems are bigger in central agencies than in ministries; and that a low level of mutual trust tends to aggravate coordination problems.     

The utilization of geographic information systems to create a site selection strategy to disseminate an older adult fall prevention program

Public health programmatic interventions are increasingly required to address the prevention needs of aging populations. Falls in adults age 65 and older are the leading cause of injury hospitalization in the U.S., and a leading cause of international fatal injuries in older adults. This project used geographic information systems (GIS) to create a site selection strategy for the dissemination and pilot evaluation of a community-based fall prevention program for older adults in Pierce County, Washington. Potential site addresses (n = 84), 2000 U.S. census data for adults ≥65 years of age, and local road networks, which were converted into service areas using actual travel time, were entered in a GIS. Potential sites were then ranked by census densities of older adults who lived within 10 min travel time. Nine sites launched the program, with the goal recruiting 20 older adult program participants at each site (n = 180). At the end of 12 months, participation exceeded program goals (n = 331). GIS can be used to determine actual travel time, and may facilitate the selection of community-based prevention program sites to maximize accessibility and utilization by targeted populations.     

The financial burden of psychosocial workplace aggression: A systematic review of cost-of-illness studies

Understanding the economic impact of psychological and social forms of workplace aggression to society could yield important insights into the magnitude of this occupational phenomenon. The objective of this systematic review was to collate, summarise, review and critique, and synthesise the cost of psychosocial workplace aggression at the individual- and societal-level. A peer-reviewed research protocol detailing the search strategy, study selection procedures and data extraction process was developed a priori. Both the academic and grey literatures were examined. To allow for basic comparison, all costs were converted and adjusted to reflect 2014 US dollars. Twelve studies, from 5 national contexts, met the inclusion criteria and were reviewed: Australia (n?=?2), Italy (n?=?1), Spain (n?=?1), the United Kingdom (n?=?3) and the United States (n?=?5). The annual cost of psychosocial workplace aggression varied substantially, ranging between $114.64 million and $35.9 billion. Heterogeneity across studies was found, with noted variations in stated study aims, utilised prevalence statistics and included costs. The review concludes that existing evidence attests to the substantial cost of psychosocial workplace aggression to both the individual and society, albeit such derived estimates are likely gross under-estimates. The findings highlight the importance of interpreting such figures within their conceptual and methodological contexts.     

The Sources and Diversity of Immigrant Population Change in Australia, 1981–2011

Australia has one of the largest percentages of immigrant populations in the developed world with a highly regulated system of immigration control and regular censuses to track their changes over time. However, the ability to explain the population change through the demographic components of immigration, emigration, and death by age and sex is complicated because of differences in measurement and sources of information. In this article, we explore three methods for reconciling the demographic accounts from 1981 to 2011 for the Australia-born and 18 foreign-born population groups. We then describe how the immigrant populations have changed and what has contributed most to that change. We find that the sources of immigrant population change have varied considerably by age, sex, country of birth, and period of immigration. Immigrants from Europe are currently the oldest and slowest-growing populations, whereas those from elsewhere are growing rapidly and exhibit relatively young population age structures. Studying these patterns over time helps us to understand the nature of international migration and its long-term contributions to population change and composition.     

Using New Technologies for Time Diary Data Collection: Instrument Design and Data Quality Findings from a Mixed-Mode Pilot Survey

The goal of this study is to examine the association between location-sharing in location based social networking (LBSN) services and social capital, such as trust, reciprocity, and network resources. A cross-sectional survey (n = 491) was conducted by adopting a simple random sampling method in 2014. The findings showed that intensity of LBSN services is positively associated with all social capital aspects. In general, compared to a group of non-users of LBSN services, those groups of users with low and high intensity of LBSN services were higher in trust, reciprocity, and network resources. Therefore, this study proposes theoretical and practical implications of location-sharing to scholars in social sciences demonstrating how use of LBSN services influences accumulation of social capital.