Modelling price paths in on-line auctions: smoothing sparse and unevenly sampled curves by using semiparametric mixed models

Summary.  On-line auctions pose many challenges for the empirical researcher, one of which is the effective and reliable modelling of price paths. We propose a novel way of modelling price paths in eBay's on-line auctions by using functional data analysis. One of the practical challenges is that the functional objects are sampled only very sparsely and unevenly. Most approaches rely on smoothing to recover the underlying functional object from the data, which can be difficult if the data are irregularly distributed. We present a new approach that can overcome this challenge. The approach is based on the ideas of mixed models. Specifically, we propose a semiparametric mixed model with boosting to recover the functional object. As well as being able to handle sparse and unevenly distributed data, the model also results in conceptually more meaningful functional objects. In particular, we motivate our method within the framework of eBay's on-line auctions. On-line auctions produce monotonic increasing price curves that are often correlated across auctions. The semiparametric mixed model accounts for this correlation in a parsimonious way. It also manages to capture the underlying monotonic trend in the data without imposing model constraints. Our application shows that the resulting functional objects are conceptually more appealing. Moreover, when used to forecast the outcome of an on-line auction, our approach also results in more accurate price predictions compared with standard approaches. We illustrate our model on a set of 183 closed auctions for Palm M515 personal digital assistants.     

User-driven innovation of an outpatient department

This paper presents experiences from a user-driven innovation process of an outpatient department in a hospital. The mixing of methods from user-driven innovation and participatory design contributed to develop an innovative concept of the spatial and organizational design of an outpatient department in a hospital. Design games and tabletop simulation seem to be powerful tools in facilitating such a participatory process.     

Restrictive Control and Information Pathologies in Organizations

Although the relation of power to knowledge is an often discussed theme, a psychological and sociological scrutiny of the issue is lacking. A new conceptual and theoretical approach to this issue is presented here that distingushes between restrictive and promotive control. Restrictive control is a form of power exertion in which one actor pushes his wishes through against the interests of another actor. In contrast, if an actor influences the other in line with his or her interests, this is called promotive control. Information pathologies, i.e., avoidable failures of distributed information processing, are introduced as an inverse measure for the quality and quantity of knowledge production. It is hypothesized that restrictive control has negative consequences for the production of new or better knowledge, because it induces information pathologies that in turn lower the effectiveness of joint action. These two hypotheses are tested in a study on 21 successful and 21 unsuccessful innovations with a dual qualitative and quantitative approach. The interpretive analysis of interviews with the main actors of each innovation case as well as the statistical analysis of questionnaire responses by the same actors strongly corroborate both hypotheses. Methodological problems, theoretical perspectives, and practical consequences are discussed.     

Implementierung von Coaching für Schulleitung und Schulaufsicht

Implementation of coaching for principals and supervisory school authorityGerman schools will have to improve the quality of their work to be able to compete on an international level. School development is also personnel development. Establishing professionalism of school executives (among others by coaching) plays a major role in this matter. First of all the author describes the implementation process of internal coaching for principals and thereafter for officers of the supervisory school authority. In doing so, he also points out problems that can arise during such a project. The evaluations of surveys prove the acceptance and importance of coaching for this target group. Finally, possible future coaching offers for school executives are addressed.     

Some Properties of the Hazard Function of the Two-Mutation Clonal Expansion Model

We discuss the hazard function of the two-mutation clonal expansion model with time-dependent parameters, with particular emphasis on identifiability of the parameters. We explicitly construct identifiable parameter combinations, and illustrate the properties of the hazard function under perturbations of the underlying biological parameters.     

Consciousness Re-Evaluated: Interpretive Theory and Feminist Scholarship*

This paper suggests that interpretive sociology should review its model of consciousness in the light of the new feminist scholarship on women's experience of self and society. The thesis of the paper is that there is a fundamental conflict in women's consciousness between meaning systems inherited from the culture and those that are acquired through lived experience. This paper demonstrates that interpretive sociology's model of consciousness does not account for the conflicts posed by the feminist perspective and suggests future issues for research.     

Setting Priorities in the National Campaign Against Drug Abuse

In its ‘National Campaign Against Drug Abuse’, the Federal Government has decided to give top priority in the 1987 financial year to preventing the use of heroin and cocaine, particularly among the young. After reviewing the drug consumption habits of North Queenslanders, we conclude that this decision does not address the most immediate drug-related health problems of the region. Our data suggest not only that legal drugs pose a far greater threat to the health and welfare of Australian society but also that drug abuse is primarily concentrated within the adult population.     

The emergence of Sub-Replacement Family Size Ideals in Europe

Period fertility started to drop significantly below replacement in most Western European countries during the 1970s and 1980s, while most fertility surveys, value studies and opinion polls have found that the number of children considered ideal for society or for one's own family has remained above two children per woman. These surveys have led to the expectation that, sooner or later, period fertility would recover in Europe. The most recent data from the Eurobarometer 2001 survey, however, suggest that in the German-speaking parts of Europe the average ideal family sizes given by younger men and women have fallen as low as 1.7 children. This paper examines the consistency and the credibility of these new findings, which – if they are indeed indications of a new trend – may alter the current discussion about future fertility trends in Europe.