Change-in-mean tests in long-memory time series: a review of recent developments

AStA Advances in Statistical Analysis - It is well known that standard tests for a mean shift are invalid in long-range dependent time series. Therefore, several long-memory robust extensions of...     

Online network monitoring

Statistical Methods & Applications - An important problem in network analysis is the online detection of anomalous behaviour. In this paper, we introduce a network surveillance method bringing...     

Piecewise linear approximation of empirical distributions under a Wasserstein distance constraint

Big data applications and Monte Carlo simulation results can nowadays easily contain data sets in the size of millions of entries. We consider the situation when the information on a large univariate data set or sample needs to be preserved, stored or transferred. We suggest an algorithm to approximate a univariate empirical distribution through a piecewise linear distribution which requires significantly less memory to store. The approximation is chosen in a computationally efficient manner, such that it preserves the mean, and its Wasserstein distance to the empirical distribution is sufficiently small.     

Control charts for multivariate spatial autoregressive models

This paper deals with spatial detection of changes in model parameters of spatial autoregressive processes. The respective sequential testing problems are formulated. Moreover, we introduce characteristic quantities to monitor means or covariances of multivariate spatial autoregressive processes. Additionally, we also take into account the simultaneous surveillance of the mean vector and the covariance matrix. The aim is to apply control charts, important tools of sequential analysis, to these quantities. The considered control procedures are based on either cumulative sums or exponential smoothing. Further, we illustrate the methodology of statistical process control studying the spectrum of additive colors in a satellite photograph. Via simulation studies, the proposed control procedures are calibrated for a predefined average run length. In addition, we compare the performance of the control procedures considering the out-of-control situation. Eventually, the control charts are applied, and the signals of the different schemes are visualized. The final results are critically discussed.     

Evidenztriangulation in der Gesundheitsforschung

The contribution starts with weaknesses of a strict quantitative methodology in social research. Especially in health research variable connections are so complex that a broader understanding of research methods seems to be necessary. The dominance of quantitative-experimental ongoing in the sense of randomized controlled trials (RCT) at the top of the evidence hierarchy is criticized and a concept of evidence triangulation in the sense of mixed methods is proposed as alternative. An example study shows the logic of this research design. An institution of drug addicts counseling and therapy is analyzed in its effects through an evaluation study, using four different methodological approaches, an experimental pre-post design, qualitative interviews with the clients, and qualitative and document analysis using qualitative content analysis are combined. Each of them is developed in criticizing and supplementing the other approaches. The mixed methods procedure therefor follows a dialectical theory of science.     

Direct and Indirect Effects of Individualism and Institutions on Homicides

Social Indicators Research - The present paper evaluates whether people in highly individualistic cultures have a lower propensity to commit homicides, using data from 70 countries. Several...     

Understanding Knowledge Activists’ Successes and Failures

Firms are increasingly relying on “knowledge activists” to facilitate the flow of knowledge. This paper discusses which initiatives by activists are most likely to succeed. It identifies a conceptual framework that illustrates the conditions essential to full knowledge sharing and illustrates its effectiveness through a selection of case studies. It concludes by saying that the rigidity and priorities of organisations often preclude the flexibility and entrepreneurism necessary for successful knowledge initiatives.