Introduction to internally consistent modeling,aggregation, inference,and policy

This special issue of the Journal of Econometrics honors William A. Barnett’s exceptional contributions to unifying economic theory with rigorous statistical inference to interpret economic data and inform public policy. It is devoted to papers that advance microeconometrics, macroeconometrics, and financial econometrics to build models to interpret evidence.     

Information flows and crashes in dynamic social networks

We develop a dynamic model of information transmission and aggregation in social networks in which continued membership in the network is contingent on the accuracy of opinions. Agents have opinions about a state of the world and form links to others in a directed fashion probabilistically. Agents update their opinions by averaging those of their connections, weighted by how long their connections have been in the system. Agents survive or die based on how far their opinions are from the true state. In contrast to the results in the extant literature on DeGroot learning, we show through simulations that for some parameterizations the model cycles stochastically between periods of high connectivity, in which agents arrive at a consensus opinion close to the state, and periods of low connectivity, in which agents’ opinions are widely dispersed.

     

Schatting van een populatiegemiddelde bij ongelijke trekkingskansen

Summary This article presents a simple method of estimating the population mean of a variate and setting approximate confidence limits when probabilities of selection are proportional to some quantity of the selected elements, which is observed along with the variate concerned. The method is closely related to the method of ratio estimators.     

The M/M\1 queue in a heavy-tailed random environment

We consider an M / M /1 queue with the special feature that the speed of the server alternates between two constant values s_L and s_H > s_L . The high-speed periods are exponentially distributed, and the low-speed periods have a regularly varying distribution. We obtain explicit asymptotics for the tail of the workload distribution. The two cases in which the offered traffic load is smaller respectively larger than the low service speed are shown to result in completely different asymptotics.     

Advances in Joint Modelling: A Review of Recent Developments with Application to the Survival of End Stage Renal Disease Patients

The use of joint modelling approaches is becoming increasingly popular when an association exists between survival and longitudinal processes. Widely recognized for their gain in efficiency, joint models also offer a reduction in bias compared with naïve methods. With the increasing popularity comes a constantly expanding literature on joint modelling approaches. The aim of this paper is to give an overview of recent literature relating to joint models, in particular those that focus on the time‐to‐event survival process. A discussion is provided on the range of survival submodels that have been implemented in a joint modelling framework. A particular focus is given to the recent advancements in software used to build these models. Illustrated through the use of two different real‐life data examples that focus on the survival of end‐stage renal disease patients, the use of the JM and joineR packages within R are demonstrated. The possible future direction for this field of research is also discussed.     

Networks and linkages among firms and organizations in the Ottawa-region technology cluster

This paper reports on a study of the networking and linkage practices of technology and non-technology firms within the Ottawa cluster. The work seeks to understand how and why particular patterns of networks and linkages evolve and it examines empirically the usage and value of networks and linkages. Previous work argues that technology firms need to be relatively more adept at developing external relationships in order to be successful than do non-technology based companies. This work, however, finds that technology firms exhibit fewer linkages than non-technology based companies do within the Ottawa cluster. The research suggests that the vitality of the Ottawa cluster could be further enhanced through the promotion of additional networking and linkages among regional firms. A key implication for management practice is that CEOs of technology-based firms should work towards establishing and maintaining additional valued relationships.     

Investment in staff development within an emergency services organisation: comparing future intention of volunteers and paid employees

Path models were evaluated to explore the impact of job satisfaction as mediator of the relationship between perceived investment in employee development (PIED) and the adequacy and availability of training on turnover intention. Models were compared for volunteers (n = 2,306) and paid employees (n = 274) within the one emergency services organisation. Results indicated that job satisfaction mediated the relationship between PIED and intention to stay for both volunteers and paid employees. PIED was a stronger predictor of job satisfaction for paid employees, while support and recognition was a stronger predictor of job satisfaction for volunteers. Results highlight the indirect role of PIED on turnover intentions. Findings also support the notion of tailored employee development programmes that enhance job satisfaction. Further, PIED may be more salient to the turnover intentions of paid employees, while support and recognition may be a key motivator of volunteers' ongoing commitment to the organisation.     

Rater source factors represent important subcomponents of the criterion construct space, not rater bias

We contrast normative accuracy and ecological perspectives on applications of the multitrait–multimethod methodology to multisource performance ratings and review existing research that provides critical tests of these perspectives. Existing research supports the ecological perspective which proposes that the rater source effects that are typically found in analysis of multisource performance ratings do not represent mere halo biases but alternative, perhaps equally valid perspectives on ratee performance. We suggest that future research view multifaceted research designs in the broader context of a prototype multidimensional data relational system such as that proposed by Lance, Baranik, Lau, and Scharlau (Lance, C. E., Baranik, L. E., Lau, A. R., & Scharlau, E. A. (in press). If it's not trait it must be method: (Mis)application of the multitrait–multimethod design in organizational research. In C. E. Lance & R. J. Vandenberg (Eds.), Statistical and methodological myths and urban legends: Received doctrine, verity, and fable in the organizational and social sciences. Mahwah, NJ: Erlbaum).