A-optimal designs for heteroscedastic multifactor regression models

Abstract

This paper searches for A-optimal designs for Kronecker product and additive regression models when the errors are heteroscedastic. Sufficient conditions are given so that A-optimal designs for the multifactor models can be built from A-optimal designs for their sub-models with a single factor. The results of an efficiency study carried out to check the adequacy of the products of optimal designs for uni-factor marginal models when these are used to estimate different multi-factor models are also reported.     

Waiting time to exhaust lottery numbers

Questions related to lotteries are usually of interest to the public since people think there is a magic formula which will help them to win lottery draws. This note shows how to compute the expected waiting time to observe specific numbers in a sequence of lottery draws and show that surprising facts are expected to occur.     

A class of bivariate regression models for discrete and/or continuous responses

ABSTRACT

A general class of models for discrete and/or continuous responses is proposed in which joint distributions are constructed via the conditional approach. It is assumed that the distributions of one response and of the other response given the first one belong to exponential family of distributions. Furthermore, the marginal means are related to the covariates by link functions and a dependency structure between the responses is inserted into the model. Estimation methods, diagnostic analysis and a simulation study considering a Bernoulli-exponential model, a particular case of the class, are presented. Finally, this model is used in a real data set.     

Strong consistency of presmoothed Kaplan–Meier integrals when covariables are present

It is known that the Kaplan–Meier estimation may be improved via presmoothing methods. In this article, we introduce an extended presmoothed Kaplan–Meier estimator in the presence of covariates. The main result is the strong consistency of general empirical integrals based on such an estimator. As applications, one can obtain a consis-tent multivariate empirical distribution under censoring, and also can obtain a consistent estimation of regression parameters. We illustrate the new estimation methods through simulations and real data analysis.     

Bayesian factor models in characterizing molecular adaptation

Assessing the selective influence of amino acid properties is important in understanding evolution at the molecular level. A collection of methods and models has been developed in recent years to determine if amino acid sites in a given DNA sequence alignment display substitutions that are altering or conserving a prespecified set of amino acid properties. Residues showing an elevated number of substitutions that favorably alter a physicochemical property are considered targets of positive natural selection. Such approaches usually perform independent analyses for each amino acid property under consideration, without taking into account the fact that some of the properties may be highly correlated. We propose a Bayesian hierarchical regression model with latent factor structure that allows us to determine which sites display substitutions that conserve or radically change a set of amino acid properties, while accounting for the correlation structure that may be present across such properties. We illustrate our approach by analyzing simulated data sets and an alignment of lysin sperm DNA.     

Bayesian influence diagnostics in radiocarbon dating

Linear models constitute the primary statistical technique for any experimental science. A major topic in this area is the detection of influential subsets of data, that is, of observations that are influential in terms of their effect on the estimation of parameters in linear regression or of the total population parameters. Numerous studies exist on radiocarbon dating which propose a value consensus and remove possible outliers after the corresponding testing. An influence analysis for the value consensus from a Bayesian perspective is developed in this article.     

Mortality analysis of persons with disabilities in Argentina by age,sex and duration of benefit, 2015–16

This article describes the differential mortality of Argentina’s disability pension beneficiaries during the 2015–16 period, based on National Social Security Administration (Administración Nacional de la Seguridad Social – ANSES) payment records. It compares data for those with an assessed disability with overall population data, as well as with available international data (from Canada, Chile, Mexico, and the United States of America). In addition to breaking down mortality rates for people with disabilities by age and sex, it also factors in duration of benefit, establishing an inverse correlation between benefit duration and mortality.     

‘Making narrative portraits: a methodological approach to analysing qualitative data’

ABSTRACT

This paper proposes the method of ‘narrative portraiture’, which, located within the wider field of narrative studies, offers an analytical tool to narrative data. Two research projects, one on disability and one on identity, are used to illustrate how the method can be applied. While the paper will focus on the methodological benefits and limitations of the approach, throughout the article we also highlight the ethical concern of representation. We suggest that through ‘narrative portraiture’ research findings can be contextualised in broader social narratives without losing sight of the unique personal qualities of the research encounter. Thus, we argue for the importance of bringing the participant and their everyday life experience into focus, highlighting that a portrayal of a sole story can be, not only a medium to understand a research phenomenon, but also a valuable research output in itself.     

Work Trajectories of Female and Male Immigrants in Spain

This article aims to examine in depth the work trajectories of individuals over time, in order to provide a wider perspective of the employment history of immigrants compared to native people, by gender and for more than one decade (2005–2017) in Spain. We use microdata (cohort and multivariate analysis) from the Labour Force Survey and carry out a comparison for three groups: the Spanish born in Spain, the Spanish born abroad, and the non-Spanish born abroad. The results confirm that the non-Spanish born-abroad group is characterized by the existence of segmented assimilation. All foreigners suffered a loss in their work trajectories, since their employment rate in 2017 has as yet neither reached the level of the last years of the previous economic expansion nor the level of the previous cohorts at the same age.     

Aesthetics of disaster as decolonial aesthetics: making sense of the effects of Hurricane María through Puerto Rican contemporary art

ABSTRACT

On 20 September 2017, Hurricane María made landfall on Puerto Rico causing unprecedented disaster. From that day onwards, the Puerto Rican multi-layered colonial, social and political context was further complicated by the traumatic acceleration of a human disaster via this natural disaster. This crystalized the urgency of using art as vehicle for (social) catharsis, a practice that continues to be used by individual artists, collectives, community organizations, art projects, and other art institutions on the island and abroad, through mural art, community paintings, art exhibitions, literature, music, and many other aesthetic expressions. This article examines, from a decolonial and critical cultural studies perspective, post-Hurricane María artistic expressions in contemporary art as decolonial aesthetics through the cathartic use of the frame of an aesthetics of disaster. It is argued that, an aesthetics of disaster aims to re-assert an artistic form that is able to accelerate the discursive nullification of a deeply rooted colonial, social and cultural problem by way of art as catharsis inspired by the way that Hurricane María unveiled these problems. The piece briefly contextualizes Puerto Rico, and it examines the idea of Puerto Rican contemporary art as catharsis. Then, it describes how Puerto Rican contemporary art exhibitions and associated aesthetic production are processing urgent post-hurricane issues through three illustrative pieces in exhibitions in PR and abroad in the United States (US). Lastly, decolonial aesthetics is reexamined and re-understood, informed by Édouard Glissant's view expressed in Poetics of Relation which aids to the conclusion that Puerto Rican contemporary art using the frame of an aesthetics of disaster functions as a powerful form of decolonial aesthetics.