Multiple Imputation describes a strategy for analyzing incomplete data that accounts for uncertainty in the missing data by replacing (imputing) each missing value by several ‘candidates’. The actual implementation of any Multiple Imputation method is typically computationally expensive which is why the concept has only really caught on around the verge of the new millennium, when the first algorithms for Multiple Imputation had become accessible.
In this article, we are going to give a rough overview of the shortcomings of methods for handling missing data prior to Rubin’s work in the late 1970s, and we explore the conceptual innovations that might have lead to Multiple Imputation based on an example, where mean imputation is the steppingstone for more advanced methods. The general concept of Multiple Imputation is explained using a simulated trivariate data set, and the imputation model is based on the standard Bayesian linear model, in order to explain the method as illustrative as possible.
We test the hypothesis that differences in social status between groups of people within a population may induce variation in insulin-like growth factor-1(IGF-1) levels and, by extension, growth in height. This is called the community effect in height hypothesis. The relationship between IGF-1, assessed via finger-prick dried blood spot, and elite level sport competition outcomes were analysed for a sample of 116 undergraduate men and women. There was a statistically significant difference between winners and losers of a competition. Winners, as a group, had higher average pre-game and post-game IGF-1 levels than losers. We proposed this type of difference as a proxy for social dominance. We found no evidence that winners increased in IGF-1 levels over losers or that members of the same team were more similar in IGF-1 levels than they were to players from other teams. These findings provide limited support toward the community effect in height hypothesis. The findings are discussed in relation to the action of the growth hormone/IGF-1 axis as a transducer of multiple bio-social influences into a coherent signal which allows the growing human to adjust and adapt to local ecological conditions.
As semi-presidentialism has become increasingly common in European democracies, so have the debates about the consequences of several of its political and institutional features. In particular, in those regimes, cohabitation between presidents and cabinets of different parties and cabinet dismissal powers on the part of presidents are thought to be a source of inter-branch conflict and government instability.However, so far, most empirical work on government survival has failed to confirm any of these expectations. This article addresses this disjuncture between theory and empirical results by making a twofold contribution.
First, it takes into account the internal diversity within semi-presidentialism, modeling the implications for government survival of different configurations between presidential powers’ of cabinet dismissal, parliament dissolution and cohabitation in European semi-presidential systems.
Second, it reconsiders traditional government survival using the competing risks framework by adding a distinction between two different types of non-electoral replacement: those where replacements imply a change in the party of the prime minister and those where they do not.Once such an approach is adopted, that presidential powers of parliamentary dissolution and cabinet dismissal indeed emerge as highly relevant for explaining government survival in these regimes.
Peer problems are common in children with special educational needs (SEN), but the reasons are poorly understood. This study aims to identify risk factors of peer problems (e.g., SEN, school setting, pro-social behaviour) for their occurrence. A subsample of 3900 children from the National Educational Panel Study in Germany was analysed. Children and parents answered the items of the Strengths and Difficulties Questionnaire (SDQ) subscales ‘peer problems’ and ‘pro-social behaviour’. Students with SEN (attending special schools or inclusive classes) were more likely to score within the abnormal range of the SDQ subscale peer problems than students without SEN. The results further show a low level of parent–child agreement on the subscale ‘peer problems’. Logistic regression analyses showed that having SEN is always an explaining variable for ‘peer problems’ and that group differences cannot be fully explained by gender, school setting or ‘pro-social behaviour’.
As a result of public discussions regarding Germany's standing on international rankings of student achievement, increased attention was focused on enhancing cognitive stimulation in preschools. There are some concerns that preschool curricula that focus more on cognitive stimulation rather than on socio-emotional skills might neglect the socio-emotional development of children. These concerns are rooted in the tradition of German preschools focussing more on the stimulation of social than of cognitive skills. This paper examines these claims by drawing on the German preschool programme ‘KiDZ’ in order to analyse the socio-emotional development (well-being, joy of learning, and worry) of children attending a preschool with a more academically oriented curriculum. This study also investigates effects of domain-specific preschool quality and if any effects of participation in KiDZ might be explained by the quality of the preschools. Positive effects of the children's participation in KiDZ are found and will be discussed.