The World's Changing Human Capital Stock: Multi‐State Population Projections by Educational Attainment

This research note presents the first global population projections by educational attainment using methods of multi‐state population projection. The educational composition of the population by age and sex and educational fertility differentials are estimated for 13 world regions, and alternative scenarios are presented to the year 2030. One of these scenarios assumes constant educational transition rates and the other assumes that all regions reach Northern American levels of enrollment rates by 2030. The strong momentum or, as the case may be, inertia in the transformation of the educational composition of a population, seen in the results, arises because education is mostly acquired at a young age. The sex bias in the educational composition, especially evident in some developing countries, is unlikely to disappear soon. China has made remarkable progress in improving educational enrollment and as a consequence by 2030 is expected to have more educated people of working age than Europe and Northern America together.     

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.     

On (n-l)-wise and joint independence and normality of n Random variables: an example

An example is given of a vector of n random variables such that any (n-1)-dimensional subvector consists of n-1 independent standard normal variables. The whole vector however is neither independent nor normal.     

Deletions in random binary search trees: A story of errors

The usual assumptions for the average case analysis of binary search trees (BSTs) are random insertions and random deletions. If a BST is built by n random insertions the expected number of key comparisons necessary to access a node is 2 ln n+O(1). This well-known result is already contained in the first papers on such ‘random’ BSTs. However, if random insertions are intermixed with random deletions the analysis of the resulting BST seems to become more intricate. At least this is the impression one gets from the related publications since 1962, and it is quite appropriate to speak of a story of errors in this context, as will be seen in the present survey paper, giving an overview on this story.     

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.     

The intersection of social protection and mobilities: a move towards a ‘Practical Utopia’ research agenda

Currently, a number of contributions in mobility studies are looking for fruitful intersections with other ‘adjacent’ approaches . In this spirit, our theoretical paper argues to study one particular aspect: the intersection of social protection and mobilities. Currently, the provision of social services in the ‘West’ is strongly entrenched within nation-state logics, which assume that clients’ immobility is a precondition of service delivery and that national citizenship is the desirable conditionality of gaining social rights. To overcome such a wide-spread conflation of social security with state security, we introduce the heuristic concept ‘social protection’. It allows social security to be imagined beyond a state-centric perspective and avoids the pitfalls of either a citizenship or a migration approach by taking on a mobility perspective. Thus, for scholars anchored in mobility studies we propose how to develop a social security perspective in a progressive way. For readers from other areas, e.g. citizenship, migration or social policy, we will show how a mobility perspective enriched by a No Border approach can overcome a narrow Western, statist and static perspective on social security. Our goal is to conceptually open up what we call a ‘practical utopia’ research agenda, one that expands our political horizons for future and present socialities.