Markov-switching generalized additive models

We consider Markov-switching regression models, i.e. models for time series regression analyses where the functional relationship between covariates and response is subject to regime switching controlled by an unobservable Markov chain. Building on the powerful hidden Markov model machinery and the methods for penalized B-splines routinely used in regression analyses, we develop a framework for nonparametrically estimating the functional form of the effect of the covariates in such a regression model, assuming an additive structure of the predictor. The resulting class of Markov-switching generalized additive models is immensely flexible, and contains as special cases the common parametric Markov-switching regression models and also generalized additive and generalized linear models. The feasibility of the suggested maximum penalized likelihood approach is demonstrated by simulation. We further illustrate the approach using two real data applications, modelling (i) how sales data depend on advertising spending and (ii) how energy price in Spain depends on the Euro/Dollar exchange rate.     

Zur Persönlichkeitsstruktur von Multiplikatoren im On- und Offline-Bereich: Steigt deren Zahl durch die Online-Kommunikation?

As a key factor, word of mouth plays an important role in the diffusion of a product in the market. Therefore, big efforts are undertaken to identify opinion leaders and embed them in the value-added- and communication-process. Various studies confirm the relevant role of the opinion leader in terms of interpersonal communication. The importance of these multipliers got even more intensified through the wide range of services in the internet. Field reports or product evaluations achieve an intensely enhanced recipient circle through opinion platforms and discussion bulletin boards. However, the diffusion of information through the internet is not determinated through the typical attributes of a classical opinion leader. So it is possible to adopt an online multiplier role without acting the same way in an offline environment. Therefore, the present study deals with the differentiation between the online multiplier and the classical opinion leader on the basis of their personality structure. The results confirm the role of the internet as a platform that enables people with a strong personality as well as people with a weak personality to act as a multiplier.     

Long and short term poverty: Is Germany a two-thirds society?

Social scientists and media commentators have expressed concern that Western countries are becoming two-thirds societies in which two-thirds enjoy the benefits of affluence, while one-third are locked into poverty or near-poverty. This paper, based on economic panel data, tests the two-thirds society hypothesis in the case of (West) Germany 1984–89. The main finding is that poverty (defined as receiving less than half of average household income) is mostly short term and that nothing like one-third are locked into poverty. On the other hand, far more people than had previously been thought are at risk of poverty. In 1984–89 only 3% were poor every year but about 25% were poor in at least one year. Germany appears to be a 75-15-10 society: 75% not poor, 15% occasionally poor but with generally adequate incomes, and 10% frequently poor or near-poor with incomes that may be considered inadequate. Analysis is based on the German Socio-Economic Panel Study (SOEP) and relates to the 8,000 people who were interviewed each year from 1984 to 1989.     

Quality of life in a European Perspective: The EUROMODULE as a New Instrument for Comparative Welfare Research

In this article, a new survey instrument for comparative welfare researchand social reporting is described, the EUROMODULE. It has been set up inintensive discussions among experts from several nations engaged inquality of life research and social reporting. By combining indicatorsof objective living conditions, subjective well-being, and quality ofsociety, with this new survey central aspects of the quality of life ofEuropean citizens can be investigated. The EUROMODULE initiative aimsat strengthening efforts to monitor and systematically analyze thecurrent state and the changes in living conditions and quality of lifein Europe in a comparative perspective. So far, data for eightEuropean countries are available.     

Does yoga engender fitness in older adults? A critical review

Interest in yoga is growing, especially among older adults. This review critically summarizes the current literature to investigate whether physical fitness and function benefits are engendered through the practice of yoga in older adults. A comprehensive search yielded 507 studies; 10 studies with 544 participants (69.6 ± 6.3 yr, 71% female) were included. Large variability in yoga styles and measurement outcomes make it challenging to interpret results across studies. Studies reported moderate improvements for gait (ES = 0.54, 0.80), balance (ES = 0.25-1.61), upper/lower body flexibility (ES = 0.25, 0.70), lower body strength (ES = 0.51), and weight loss (ES = 0.73, 0.99).Yoga may engender improvements in some components of fitness in older adults. However, more evidence is needed to determine its effectiveness as an alternative exercise to promote fitness in older adults. Further investigation into yoga as an exercise activity for older adults is warranted.     

Proportional hazard regression models for point processes: an analysis of nuclear power plant operations in Europe

The safety and reliability of nuclear power have been hotly debated in the last 30 years. Compared with physical outputs of production, such as electricity, safety and reliability are not easily measurable. This paper considers reliability, defined as the hazard of an unplanned shutdown, and addresses the measurability problem by introducing a generalization of Poisson regression models to analyze the occurrence of unplanned shutdowns interrupting operating spells in European nuclear power plants between 1981 and 1986.     

Intensive gamblers on German-style slot-machines

Results of German-style slot-machine gambling are reported, stemming from seven individual surveys in representatively sampled households (N=7,643). The aim of the inquiry was the reexamination of studies of the number of gamblers in the population together with gambling hours spent per week by active gamblers. The results are largely identical with already known data. Of persons of voting age or older, 10.2% are active gamblers (4.6 million; having gambled at least once within the last 3 months). Of the active gamblers 0.7% are intensive gamblers (5 hours and more per week). These persons number approximately 32,000 in the Federal Republic of Germany, or from 12,000 to 71,000 (95% confidence interval). In addition to the frequency distributions, interactions with socio-demographic characteristics were examined, and an estimate was made for the prevalence of intensive gamblers with severe stress.This article was first published in Germany: Bühringer, G. & Konstanty, R., (1989) Vielsspieler an Geldautomaten in der Bundesrepublik Deutschland, Suchtgefahren 35, 1–13.     

Relative efficiency of OLSE and COTE for seasonal autoregressive disturbances

The efficiency of OLSE relative to GLSE and COTE is studied in the case in which regressors are splines used to explain seasonal influences. It is thereby shown that efficiency measured as the ratio of total or generalized variances is independent of the actual design of splines. Furthermore, for positive autocorrelation, COTE is always worse than OLSE.