The integrator’s new advantage – The reassessment of outsourcing and production competence in a global telecom firm

For a long time, the telecom equipment industry has been at the forefront of outsourcing and relocating production operations to contract manufacturing firms located in Asia and Eastern Europe. Recently, however, leading firms have begun to revise this strategy, based on their recognition of the continual importance of technological leadership and integration capabilities. Using a case study of a key company, this paper explores the dynamics of outsourcing and production strategies in the telecom equipment industry. One of the central aspects under study is the interaction of product development with industrialisation and production. The paper analyses issues such as component standardisation versus differentiation and technological integration, the value of deep integration capabilities for cost reductions, and why production competence and the rapid industrialisation of products incorporating new technologies have acquired renewed importance, despite the global trend towards lowest-cost locations.     

Arrow’s theorem in judgment aggregation

In response to recent work on the aggregation of individual judgments on logically connected propositions into collective judgments, it is often asked whether judgment aggregation is a special case of Arrowian preference aggregation. We argue for the converse claim. After proving two impossibility theorems on judgment aggregation (using “systematicity” and “independence” conditions, respectively), we construct an embedding of preference aggregation into judgment aggregation and prove Arrow’s theorem (stated for strict preferences) as a corollary of our second result. Although we thereby provide a new proof of Arrow’s theorem, our main aim is to identify the analogue of Arrow’s theorem in judgment aggregation, to clarify the relation between judgment and preference aggregation, and to illustrate the generality of the judgment aggregation model.     

Visual analysis of categorical time series

While at least some standard graphical tools do exist for cardinal time series analysis, little research effort has been given directed towards the visualization of categorical time series. The repertoire of such visual methods is nearly exclusively restricted to few isolated proposals from computer science and biology. This article aims at presenting a toolbox of known and newly developed approaches for analysing given categorical time series data visually. Among these tools, especially the rate evolution graph, the circle transformation, pattern histograms and control charts are promising.     

The relationship of work stressors, coping and social support to psychological symptoms among female secretarial employees

A conceptual framework is advanced that assumes that psychological symptoms emerge within multiple contexts, such as the workplace, and are influenced by the interplay of individual and situational risk and protective factors over time. This framework was utilized to examine the impact of work and work-family role stressors, coping, and work-related social support on psychological symptoms among 239 female, secretarial employees in the USA, using both cross-sectional and longitudinal structural equation models. Work stressors and avoidance coping were viewed as risk factors, and active coping and social support as protective factors. Work stressors contributed substantially to increased symptoms, primarily through a direct pathway in the cross-sectional model, but also indirectly to both Time 1 and Time 2 symptoms (4 months later) via pathways through active and avoidance coping. In both models, avoidance coping also predicted increased symptoms. Avoidance coping also served to partially mediate the relationship between work stressors and symptoms in the cross-sectional model, but not in the longitudinal model. Active coping was related to fewer psychological symptoms in both models, thereby reducing the negative effect of work stressors on symptoms. Likewise, work-related social support served an indirect protective function by contributing to lower levels of reported work stressors and greater use of active coping. Work stressors but not active coping mediated the relationship between social support and symptoms. Implications for future research and workplace interventions are discussed.     

Objective priors for causal AR(p) with partial autocorrelations

We consider the problem of deriving formal objective priors for the causal/stationary autoregressive model of order p. We compare the frequentist behaviour of the most common default priors, namely the uniform (over the stationarity region) prior, the Jeffreys’ prior and the reference prior.     

Properties of a class of binary ARMA models

We investigate a class of ARMA-type models for stationary binary time series developed in [M. Kanter, Autoregression for discrete processes mod 2, J. Appl. Probabil. 12 (1975), pp. 371–375, E. McKenzie, Extending the correlation structure of exponential autoregressive-moving-average processes, J. Appl. Prob. 18 (1981), pp. 181–189.], which we shall refer to as BinARMA models. This sparsely parameterized model family is even able to deal with negative autocorrelations, which occur in language modelling, for instance. While the autocorrelation structure of the BinAR(p) models has been studied before in [M. Kanter, Autoregression for discrete processes mod 2, J. Appl. Probabil. 12 (1975), pp. 371–375], we shall present new results on the autocorrelation structure of general BinARMA models. These results simplify in the BinMA(q) case, while the known results concerning BinAR(p) models are included as a special case. A real-data example indicates possible fields of application of these models.     

Panel Unit Root Tests in the Presence of Cross-Sectional Dependencies: Comparison and Implications for Modelling

Several panel unit root tests that account for cross-section dependence using a common factor structure have been proposed in the literature recently. Pesaran's (2007 Pesaran , M. H. ( 2007 ). A simple panel unit root test in the presence of cross section dependence . Journal of Applied Econometrics 22 : 265 – 312 .[Crossref], [Web of Science ®] , [Google Scholar]) cross-sectionally augmented unit root tests are designed for cases where cross-sectional dependence is due to a single factor. The Moon and Perron (2004 Moon , H. R. , Perron , B. (2004). Testing for a unit root in panels with dynamic factors. Journal of Econometrics 122:81–126.[Crossref], [Web of Science ®] , [Google Scholar]) tests which use defactored data are similar in spirit but can account for multiple common factors. The Bai and Ng (2004a Bai , J. , Ng , S. ( 2004a ). A PANIC attack on unit roots and cointegration . Econometrica 72 : 1127 – 1177 .[Crossref], [Web of Science ®] , [Google Scholar]) tests allow to determine the source of nonstationarity by testing for unit roots in the common factors and the idiosyncratic factors separately. Breitung and Das (2008 Breitung , J. , Das , S. ( 2008 ). Testing for unit roots in panels with a factor structure . Econometric Theory 24 : 88 – 108 .[Crossref], [Web of Science ®] , [Google Scholar]) and Sul (2007 Sul , D. ( 2007 ) . Panel Unit Root Tests Under Cross Section Dependence with Recursive Mean Adjustment . Mimeo : University of Auckland . [Google Scholar]) propose panel unit root tests when cross-section dependence is present possibly due to common factors, but the common factor structure is not fully exploited.

This article makes four contributions: (1) it compares the testing procedures in terms of similarities and differences in the data generation process, tests, null, and alternative hypotheses considered, (2) using Monte Carlo results it compares the small sample properties of the tests in models with up to two common factors, (3) it provides an application which illustrates the use of the tests, and (4) finally, it discusses the use of the tests in modelling in general.     

Borda and Condorcet: Some Distance Results

This paper provides a distance based analysis of the Borda rule with respect to Condorcet’s criterion. It shows that the minimal Condorcet consistency present in the Borda rule, whenever a Condorcet winner (the alternative that wins against every other alternative in a pairwise contest) exists, disappears in the case of voting cycles. First, it is shown that for certain preference profiles the Borda winner is furthest from being a Condorcet winner. Second, it is shown that there exist preference profiles for which the Borda winner is closest from being a Condorcet loser (the alternative that loses against every other alternative in a pairwise contest).