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.     

Mammals in and around suburban yards,and the attraction of chicken coops

Urban areas are an important and growing land use class. Nearly 5 % of the world is covered with urban development and residential yards make up a large proportion of that area. Yards have unique but homogenous biological characteristics and are known to be rich with bird fauna, but little is known about backyard mammals. We used camera traps to sample mammal communities in backyards and urban woodlots in Raleigh-Durham, North Carolina, USA and related species activity to yard characteristics and levels of neighborhood development. We found a vibrant community of smaller herbivores and carnivores using residential yards in urban areas, but larger ungulates and carnivores were only detected on the urban fringe, or in woodlots. Backyard chicken coops were positively correlated with raccoon activity but were not positively correlated with other predators, suggesting that chicken coops are attracting raccoons, but not other predators, to yards. Fenced-in dogs were negatively correlated with most mammals suggesting that confined dogs keep mammals out of yards. Unfenced dogs and fences without dogs, showed a more varied relationship with mammal activity. These results show an encouraging sign of how humans can coexist with wildlife, even in urban areas, and suggest some strategies to minimize conflict regarding backyard chicken coops and dogs.     

A Comparison of Accelerated and Traditional MSW Students: Twenty Years Later

Abstract

There has been concern about the ideal length of time to effectively offer graduate content. Programs of less than two full years have been suspect. Thus study reports on two groups of social workers in the same program who have been professionally active for over twenty years. They completed the master's requirements under two different time conditions: One group completed study in twelve months; the other in the traditional two year period. The accelerated group reported the five major curriculum areas were more useful in their practice. In addition, they reported higher long-range achievement scores on the identical objectives of both programs.     

‘We Don’t Need Another Hero’

The collapse of the Berlin Wall is usually associated with images of progress, with falling autocrats and rising liberties. But things are not quite as straightforward if scrutinized from the vantage-point of women. Despite their unusually active participation in the mass protests of 1989, women in the eastern part of Germany suffered a series of setbacks in the subsequent unification process, most notably in the realms of reproductive rights, employment opportunities and access to affordable day-care. This article engages contending feminist approaches in East and West Germany in an attempt to highlight the controversial but central role the concept of patriarchy occupies in understanding the gendered effects of unification. To recognize the significance of patriarchal domination is not to deny that some forms of dissent - and even emancipatory transformation - have taken place. It does, however, necessitate an understanding of gender-related domination and resistance that focuses not only on heroic revolutionary events and on political, legal and institutional features, but also, and perhaps even primarily, on relatively mundane daily struggles that take place over values and societal expectations.     

A copula-based multivariate hidden Markov model for modelling momentum in football

AStA Advances in Statistical Analysis - We investigate the potential occurrence of change points—commonly referred to as “momentum shifts”—in the dynamics of football...     

Why is Six Sigma so successful?

There can be little doubt that Motorola, General Electric, Black and Decker, Allied Signal (now Honeywell), ABB and Bombardier, have achieved impressive business performance in recent years. Their annual reports document this success. Furthermore, in several cases, the Annual Report clearly attributes this success to having followed a Six Sigma strategy. Not surprisingly, many other companies wish to learn what Six Sigma can do for them, and their first question is 'What exactly is Six Sigma?'. Unfortunately it is rather difficult, if not impossible, to define Six Sigma in one or two sentences. This paper identifies the essential elements of Six Sigma. Some are obvious, such as the extensive use of statistical techniques by employees known as Blackbelts. However, other more subtle, but very important, features of Six Sigma are concealed within the business culture of these successful companies. It is clear to those who have participated in this success, that any company embarking on Six Sigma will not succeed if it focuses on statistics whilst failing to develop a supporting culture.     

Managing by fact

Some organisations claim to have a "management-by-fact" culture, meaning that managerial decisions are based on data, rather than assumptions or opinions. Roland Caulcutt explains how an organisation can work towards this goal by using a simple graphical technique.     

The meaning of consumption

Three samples of subjects, varying in involvement in daily economic matters, were asked to rank order 32 activities according to whether each activity meant consumption. Spending activities were central in the meaning of consumption, but no major intersample difference could be obtained.Smallest Space Analysis showed that ‘expenditure vs non-expenditure’ and ‘necessity vs non-necessity’ were the most important dimensions along which people's thinking about consumption was organised. A third dimension, ‘stress vs non-stress’ had an uncertain dimensional interpretation and is only presented in a tentative way.Using Procrustean Individual Difference Scaling it was shown that the three samples did not differ in dimensional saliences, but a vector-weighting transformation indicated some structural differences in the activity space. Yet no systematic influence of the involvement in daily economics on the meaning of consumption has been found. Finally, a conceptual hierarchical model for the subjective meaning of consumption is proposed.