Model Averaging for Prediction With Fragmentary Data

ABSTRACT

One main challenge for statistical prediction with data from multiple sources is that not all the associated covariate data are available for many sampled subjects. Consequently, we need new statistical methodology to handle this type of “fragmentary data” that has become more and more popular in recent years. In this article, we propose a novel method based on the frequentist model averaging that fits some candidate models using all available covariate data. The weights in model averaging are selected by delete-one cross-validation based on the data from complete cases. The optimality of the selected weights is rigorously proved under some conditions. The finite sample performance of the proposed method is confirmed by simulation studies. An example for personal income prediction based on real data from a leading e-community of wealth management in China is also presented for illustration.     

Axial solutions for multiple objective linear problems. An application to target setting in DEA models with preferences

In this paper we introduce the class of axial solutions for multiple objective optimization problems in contexts in which partial information on preference weights is available. These solutions combine the use of an improvement axis to direct the search of the most preferred result with the concept of efficiency with respect to preference information.     

Approximate Likelihoods for Generalized Linear Errors-in-variables Models

When measurement error is present in covariates, it is well known that naïvely fitting a generalized linear model results in inconsistent inferences. Several methods have been proposed to adjust for measurement error without making undue distributional assumptions about the unobserved true covariates. Stefanski and Carroll focused on an unbiased estimating function rather than a likelihood approach. Their estimating function, known as the conditional score, exists for logistic regression models but has two problems: a poorly behaved Wald test and multiple solutions. They suggested a heuristic procedure to identify the best solution that works well in practice but has little theoretical support compared with maximum likelihood estimation. To help to resolve these problems, we propose a conditional quasi-likelihood to accompany the conditional score that provides an alternative to Wald's test and successfully identifies the consistent solution in large samples.     

THE CHOICE BETWEEN SETS OF REGRESSORS

This paper examines the choice of critical values for testing both non-sequential and nested sequential sets of constraints in the standard linear regression model. Modest increases in (e.g.) t-ratio critical values relative to their one-off values are often sufficient to maintain proper size. A Bayesian decision-theoretic approach, highlighted by the Schwarz (1978) criterion, provides a framework for deriving consistency and asymptotic local power properties of both forms of testing (data mining) algorithms.     

‘My dad hangs out of helicopter doors and takes pictures of oil platforms': Children's accounts of parental work in the oil and gas industry

Against the backdrop of the acceleration in pace of work and family life over the last decade, and the accompanying intensification of the work-family debate, this paper argues for the need to include children as stakeholders in the work-family debate. The ethnographic study on which this paper is based brings together children, family, work and community to explore interrelationships between workplace change, parental employment and family life in the oil and gas industry in Scotland. This paper focuses specifically on children's accounts of parental work and the work-family interface. Children, aged 8-12, were seen in schools and at home. Eight focus groups were conducted in two primary schools with 33 children. Nineteen of the families of these children participated in follow-up home interviews, in which 21 focus group children and a further 21 children (siblings, cousins and friends) were seen at home. Multiple methods were used: pictures and photographs of 'work', drawings, a poem, vignettes, word games, and a 'life mode technique'. The paper discusses children's concepts of 'work'; children's knowledge of parental work and the oil industry; children's perceptions of the impact of work on their parents; children's accounts of the effects of parental work on them and the importance of 'family time'; children's own work aspirations; and children's views and values about involvement, communication and decision making regarding parental work. Similarities and differences between children's accounts are highlighted. Sobre el telón de fondo del aumento de paso del trabajo y de la vida familiar en esta última década, y la intensificación del debate 'trabajo/familia' que lo acompaña, este artículo aboga por lo necesidad de incluir a los niños como partes interesadas en tal debate. El estudio etnográfico sobre el cual se basa este artiículo reune a los niños, la familia, el trabajo y la comunidad para explorar las interrelaciones entre el cambio de lugar del trabajo, el empleo de los padres y la vida familiar en la industria petrolera y del gas natural en Escocia. Este artículo se centra específicamente en las cuentas de unos niños del trabajo de los padres y de la interrelación entre el trabajo y la familia. Se entrevistaron a unos niños de 8—12 anos de edad en la escuela y en casa. Se realizaron ocho grupos de enfoque con 33 niños en dos escuelas de estudios primarios. De las familias de estos niños, 19 participaron en entrevistas de seguimiento, en las cuales 21 niños de los grupos de enfoque y 21 niños más (hermanos, primos y amigos,) fueron entrevistados en casa. Se emplearon múltiples métodos: ilustraciones y fotografías de ‘trabajo', dibujos, un poema, estampas, juegos con palabras y una ‘técnica modo de vida'. El artículo trata de los conceptos de los niños del trabajo; los conocimientos de los niños del trabajo de los padres y de la industria petrolera; las percepciones de los niños del efecto del trabajo en sus padres; las cuentas de los niños de los efectos del trabajo de los padres en los mismos niños y de la importancia del ‘tiempo para la familia'; las propias aspiraciones del los niños acerca del trabajo; y los puntos de vista y los valores de los niños sobre la participación, la comunicación y la toma de decisiones acerca del trabajo de los padres. Se ponen del relieve los elementos en común y las diferencias entre las cuentas de los niños.     

A case-based distance method for screening in multiple-criteria decision aid

Screening is a process of multiple-criteria decision aid (MCDA) in which a large set of alternatives is reduced to a smaller set that most likely contains the best choice. We propose screening using a distance model calibrated on the basis of the decision-maker's own judgement. Viewing MCDA as preference aggregation based on consequence data, we define consequence and preference expressions (values and weights) and describe how they are aggregated. Then we define screening and explain some of its properties. Using an appropriate definition of distance, our case-based distance method screens a set of alternatives using criterion weights and a distance threshold obtained by quadratic optimization using the decision-maker's selection of alternatives from a test set. This case-based method can elicit the decision maker's preferences more expeditiously and accurately than direct inquiry. An application in water supply planning is used to demonstrate the procedure.     

Unit Root Tests in the Presence of Multi-Variance Break and Level Shifts That Have Power Against the Piecewise Stationary Alternative

Structural breaks in the level as well as in the volatility have often been exhibited in economic time series. In this paper, we propose new unit root tests when a time series has multiple shifts in its level and the corresponding volatility. The proposed tests are Lagrangian multiplier type tests based on the residual's marginal likelihood which is free from the nuisance mean parameters. The limiting null distributions of the proposed tests are the χ²distributions, and are affected not by the size and the location of breaks but only by the number of breaks.

We set the structural breaks under both the null and the alternative hypotheses to relieve a possible vagueness in interpreting test results in empirical work. The null hypothesis implies a unit root process with level shifts and the alternative connotes a stationary process with level shifts. The Monte Carlo simulation shows that our tests are locally more powerful than the OLSE-based tests, and that the powers of our tests, in a fixed time span, remain stable regardless the number of breaks. In our application, we employ the data which are analyzed by Perron (1990), and some results differ from those of Perron's (1990).     

Dominance and Efficiency in Multicriteria Decision under Uncertainty

This paper proposes several concepts of efficient solutions for multicriteria decision problems under uncertainty. We show how alternative notions of efficiency may be grounded on different decision contexts, depending on what is known about the Decision Maker's (DM) preference structure and probabilistic anticipations. We define efficient sets arising naturally from polar decision contexts. We investigate these sets from the points of view of their relative inclusions and point out some particular subsets which may be especially relevant to some decision situations.     

Understanding the socio-economic distribution of multiple deprivation: An application of self-organising maps

In this paper we seek to contribute to recent efforts to develop and implement multi-dimensional approaches to social exclusion by applying self-organising maps (SOMs) to a set of material deprivation indicators from the Irish component of EU-SILC. The first stage of our analysis involves the identification of sixteen clusters that confirm the multi-dimensional nature of deprivation in contemporary Ireland and the limitations of focusing solely on income. In going beyond this mapping stage, we consider both patterns of socio-economic differentiation in relation to cluster membership and the extent to which such membership contributes to our understanding of economic stress. Our analysis makes clear the continuing importance of traditional forms of stratification relating to factors such as income, social class and housing tenure in accounting for patterns of multiple deprivation. However, it also confirms the role of acute life events and life cycle and location influences. Most importantly, it demonstrates that conclusions relating to the relative impact of different kinds of socio-economic influences are highly dependent on the form of deprivation being considered. Our analysis suggests that debates relating to the extent to which poverty and social exclusion have become individualized should take particular care to distinguish between different kinds of outcomes. Further analysis demonstrates that the SOM approach is considerably more successful than a comparable latent class analysis in identifying those exposed to subjective economic stress.