Semi-parametric segmentation of multiple series using a DP-Lasso strategy

We consider a semi-parametric approach to perform the joint segmentation of multiple series sharing a common functional part. We propose an iterative procedure based on Dynamic Programming for the segmentation part and Lasso estimators for the functional part. Our Lasso procedure, based on the dictionary approach, allows us to both estimate smooth functions and functions with local irregularity, which permits more flexibility than previous proposed methods. This yields to a better estimation of the functional part and improvements in the segmentation. The performance of our method is assessed using simulated data and real data from agriculture and geodetic studies. Our estimation procedure results to be a reliable tool to detect changes and to obtain an interpretable estimation of the functional part of the model in terms of known functions.     

Minimax properties of beta kernel estimators

In this paper, we are interested in the study of beta kernel density estimators from an asymptotic minimax point of view. These estimators allows to estimate density functions with support in [0,1]. It is well-known that beta kernel estimators are - on the contrary of classical kernel estimators - “free of boundary effect” and thus are very useful in practice. The goal of this paper is to prove that there is a price to pay: for very regular density functions or for certain losses, these estimators are not minimax. Nevertheless they are minimax for classical regularities such as regularity of order two or less than two, supposed commonly in the practice and for some classical losses.     

The resentful undergrowth of nostalgia: Ontological insecurity,relative deprivation and powerlessness

This article untangles competing conceptualisations of nostalgia and identifies a specific form of collective-restorative nostalgia as politically significant. We argue that the link between resentment and this type of nostalgia emerges from their joint critique of the socio-political realities of the present. Nostalgia provides spatial and temporal orientations for a group's experiences of resentment through highly selective recollections of the heartland and an idealised golden age. We hypothesize that nostalgia leverages the heartland and the golden age to formulate claims for recognition and restored status on behalf of those who feel left behind by late modernity. Next, the article uses structural equation modelling and the 2019 Belgian National Election Study to reveal how resentment (consisting of ontological insecurity, group relative deprivation, and powerlessness) mediates between structural characteristics and nostalgia. Our findings suggest that each component of resentment individually contributes to explaining the nostalgia of less educated and economically deprived individuals.     

The Italian Regional Well-Being in a Multi-expert Non-additive Perspective

This paper designs a multidimensional index of well-being for 20 Italian regions, based on a set of 41 indicators organized in an original hierarchical structure, a decision-tree whose four main pillars are Economy, Society, Environment and Health. Our novel approach combines the objective dimension of the evaluation (a comprehensive set of statistical indicators) within a flexible non-additive aggregation model (the Choquet integral) characterized with the preferences of informed Italian stakeholders. Adopting the Choquet integral allows us to overcome the well-known limitations embedded in the linear models, by assigning a weight (capacity) to any coalitions of dimensions, and by allowing a different degree of substitutability within each decision node in the tree. The weights and the parameters for the aggregation are elicited through a computer-based nominal group technique, a method which reduces the occurrences of drastically dissenting valuations and the potential expert-selection bias. Our results show that experts’ perception of synergies and redundancies is quite heterogeneous between levels and nodes in the tree. Moreover, well-being measures are much influenced by the degree of substitutability embedded in the experts’ preferences. Overall, the Italian picture looks more heterogeneous when analysed through the Choquet integral, with respect to a linear model.     

Infants' Individuation of Rigid and Plastic Objects Based on Shape

Recent research suggests that 12‐month‐old infants use shape to individuate the number of objects present in a scene. This study addressed the question of whether infants would also rely on shape when shape is only a temporary attribute of an object. Specifically, we investigated whether infants realize that shape changes reliably indicate identity changes only in the case of rigid objects, but not in the case of deformable plastic objects. Twelve‐month‐old infants observed how either a rigid or a plastic object was placed in a box. When searching the box, they retrieved either an object with the same (no‐switch event) or with a different shape (switch event). Infants correctly inferred two distinct objects in the switch event in the case of rigid objects, but not in the case of plastic objects. A control experiment confirmed that this result was not due to a lack of salience of the shape transformation. Thus, infants' re‐searching behavior indicated that they viewed shape as being diagnostic in the individuation process of rigid objects only.     

High-dimensional VAR with low-rank transition

Statistics and Computing - We propose a vector auto-regressive model with a low-rank constraint on the transition matrix. This model is well suited to predict high-dimensional series that are...     

LASSO-type estimators for semiparametric nonlinear mixed-effects models estimation

Parametric nonlinear mixed effects models (NLMEs) are now widely used in biometrical studies, especially in pharmacokinetics research and HIV dynamics models, due to, among other aspects, the computational advances achieved during the last years. However, this kind of models may not be flexible enough for complex longitudinal data analysis. Semiparametric NLMEs (SNMMs) have been proposed as an extension of NLMEs. These models are a good compromise and retain nice features of both parametric and nonparametric models resulting in more flexible models than standard parametric NLMEs. However, SNMMs are complex models for which estimation still remains a challenge. Previous estimation procedures are based on a combination of log-likelihood approximation methods for parametric estimation and smoothing splines techniques for nonparametric estimation. In this work, we propose new estimation strategies in SNMMs. On the one hand, we use the Stochastic Approximation version of EM algorithm (SAEM) to obtain exact ML and REML estimates of the fixed effects and variance components. On the other hand, we propose a LASSO-type method to estimate the unknown nonlinear function. We derive oracle inequalities for this nonparametric estimator. We combine the two approaches in a general estimation procedure that we illustrate with simulations and through the analysis of a real data set of price evolution in on-line auctions.     

Differentiation of welfare regimes: The case of Italy

The different welfare system classifications mainly address systems on the national level, while the local levels have not been considered in any great detail. The welfare reform measures adopted in some countries have led to more autonomy on the local level. Consequently, local authorities have adopted different social policies and developed diverse welfare services. This article addresses the case of Italy and shows that classifying a welfare regime by considering only the national level can lead to important local features being missed that are indeed relevant for its classification. The units of analysis are the 20 administrative regions of Italy. The results demonstrate that the Italian welfare system is far from being a homogeneous system and that the resources available on the local level have a considerable effect on the level of the welfare services provided. These results show that more attention needs to be directed at the local level.     

Why Do Aid Agencies Exist?

This article seeks to explain the organisational set‐up of foreign aid delivery from a Coasian perspective: Why are there many and different aid organisations and not just one? Why is foreign aid not transferred directly from donor to beneficiary? With zero transaction costs and fully shared preferences between donors and beneficiaries, there would be no need for aid agencies. Their role is not so much to transfer funds or goods and services to developing countries, but (a) to reduce ex‐ante transaction costs and (b) to mediate between the diverging preferences of donors and recipients, and package aid flows in a contract that reduces ex‐post uncertainties for donors. Outcomes differ according to types of agencies and aid delivery instruments.     

Children's participation in post-divorce decision-making: The role of conflict and attachment

Increased child participation in decision-making about custody and visitation when parents separate is an explicit political goal. This study delineates central family processes associated with child participation in post-divorce decision-making, both in mediation and in the home. Children recruited to the Dynamics of Family Conflict Study at Norwegian family counselling centres (7–15 years, n = 554) completed surveys about interparental conflict, attachment security and whether they had been invited to participate in mediation and share their views at home. Results showed a strong correlation between the two decision-making arenas as children who were invited to participate in mediation were also more likely to have been asked about their views at home, and vice versa. Mixed-effects logistic regression analyses indicated that attachment security to mothers predicted that children were invited to participate in mediation. Older children were more likely to have been invited to participate both at home and in mediation. More child-related interparental conflicts predicted that children did not know if they had been consulted at home. The study points to the need for developing better practices for including younger children.