On the Run Length of a State-Space Control Chart for Multivariate Autocorrelated Data

The literature on statistical process control (SPC) describes the negative effects of autocorrelation in terms of the increase in false alarms. This has been treated by the individual modeling of each series or the application of VAR models. In the former case, the analysis of the cross correlation structure between the variables is altered. In the latter, if the cross correlation is not strong, the filtering process may modify the weakest relations. In order to improve these aspects, state-space models have been introduced in multivariate statistical process control (MSPC). This article presents a proposal for building a control chart for innovations, estimating its average run length to highlight its advantages over the VAR approach mentioned above.     

Análisis de la contextualización del comportamiento adaptativo en el retraso mental: Comparación entre contexto familiar e institucional

Resumen

Este estudio se dirige a contrastar las diferencias en el comportamiento adaptativo de los sujetos retrasados que son producto de los diferentes contextos en los que éste es emitido. En este caso, el contexto se entiende como los aspectos físicos y sociales del lugar en el que inmediatamente se produce la conducta. Esta perspectiva molecular del contexto ha permitido detectar diferencias en el comportamiento adaptativo en términos de lenguaje receptivo y lenguaje expresivo. La muestra utilizada fueron 71 sujetos evaluados a través del West Virginia assessment and tracking system.     

A Case Study of De-randomization Methods for Combinatorial Approximation Algorithms

We study three different de-randomization methods that are often applied to approximate combinatorial optimization problems. We analyze the conditional probabilities method in connection with randomized rounding for routing, packing and covering integer linear programming problems. We show extensions of such methods for non-independent randomized rounding for the assignment problem. The second method, the so-called random walks is exemplified with algorithms for dense instances of some NP problems. Another often used method is the bounded independence technique; we explicit this method for the sparsest cut and maximum concurrent flow problems.     

A multivariate uniformity test for the case of unknown support

A test for the hypothesis of uniformity on a support S⊂ℝ ^d is proposed. It is based on the use of multivariate spacings as those studied in Janson (Ann. Probab. 15:274–280, 1987). As a novel aspect, this test can be adapted to the case that the support S is unknown, provided that it fulfils the shape condition of λ-convexity. The consistency properties of this test are analyzed and its performance is checked through a small simulation study. The numerical problems involved in the practical calculation of the maximal spacing (which is required to obtain the test statistic) are also discussed in some detail.     

Factorial Validity and Invariance of the Rosenberg Self-Esteem Scale Among Portuguese Youngsters

The purpose of the present study was to examine the reliability, factorial validity and measurement invariance (across gender, age and physical activity participation) of a Portuguese version of the Rosenberg Self-Esteem Scale (RSES). The sample consisted of 1,763 Portuguese youngsters (731 male and 1,032 female) with ages between 15 and 20 years. Reliability estimate for the one-factor solution was .845, although some proposed RSES’s underlying dimensions were lower than .70. Confirmatory factor analysis revealed that the best-fitting model was a single self-esteem factor, plus simultaneous correlated uniqueness for positively and negatively worded items. Multigroup analysis supported measurement invariance across age and physical activity participation, and partial metric invariance across gender, as three items failed to show metric equivalence. These results provide evidence that RSES has excellent psychometric properties and it is a valid self-esteem measure to be used among Portuguese youngsters.     

Characterizations of discrete distributions based on conditional expectations of record values

r -th record values subject to (r + 1)-th record values, record mean function, from a distribution of discrete type. We give some properties of the record mean function and an explicit expression for the distribution function based on its record mean function, which allows us to characterize particular discrete distributions using the record mean functions. Received: January 4, 1999; revised version: September 27, 1999     

Ranking sets additively in decisional contexts: an axiomatic characterization

Ranking finite subsets of a given set X of elements is the formal object of analysis in this article. This problem has found a wide range of economic interpretations in the literature. The focus of the article is on the family of rankings that are additively representable. Existing characterizations are too complex and hard to grasp in decisional contexts. Furthermore, Fishburn (1996), Journal of Mathematical Psychology 40, 64–77 showed that the number of sufficient and necessary conditions that are needed to characterize such a family has no upper bound as the cardinality of X increases. In turn, this article proposes a way to overcome these difficulties and allows for the characterization of a meaningful (sub)family of additively representable rankings of sets by means of a few simple axioms. Pattanaik and Xu’s (1990), Recherches Economiques de Louvain 56, 383–390) characterization of the cardinality-based rule will be derived from our main result, and other new rules that stem from our general proposal are discussed and characterized in even simpler terms. In particular, we analyze restricted-cardinality based rules, where the set of “focal” elements is not given ex-ante; but brought out by the axioms.      

Race, ethnicity, gender, and generational factors associated with the coming-out process among lesbian, and bisexual individuals

Age at coming out among gay/lesbian/bisexual (GLB) persons and sexual debut with same-gendered partners has typically been investigated in samples that do not reflect the racial and ethnic diversity of these communities. Addressing this limitation, data were collected from a diverse sample of men and women attending large-scale GLB community events in New York and Los Angeles in 2003 (N = 2,733). Compared to older cohorts, younger cohorts (18-24 year olds) of both men and women reported significantly earlier ages for sexual debut with same-gendered partners, and earlier ages for coming out to themselves and to others. Also, women began the process at later ages than men, as they reported coming out to themselves and sexual debut with a same-gender partner approximately two years later than men. There were no racial or ethnic differences in age out to self or others; however, persons of color were less likely to be out to their parents. Service providers, sexuality educators, and researchers should attend to the diversity in experience of coming out among GLB populations as they relate to the individuals gender, age, and racial and ethnic backgrounds.     

Gender segregation and the wage gap in Portugal: an analysis at the establishment level

Using a large linked employer-employee data set, this paper aims at quantifying the trend in worker segregation at the establishment level and its impact on wages in Portugal over a fifteen year period. We concentrate on the gender dimension, to answer the questions: What is the level of gender segregation across establishments in the Portuguese labor market and how has it evolved over time? What is the impact of segregation on wages? Is that impact different for men and women? Systematic and random components of segregation are computed. We use standard wage decomposition techniques to evaluate the impact of the composition of the labor force at the establishment level on wages. The results reveal a high degree of systematic gender segregation. A higher proportion of females in the establishment lowers females’ wages while, on the contrary, it raises males’ wages. The evidence gathered is consistent with the taste-based model of employer behavior and with the theory of sorting of workers across establishments based on their productivity.     

Coalition Formation and Stability

This paper studies a class of NTU coalition formation games in which every player’s payoff depends only on the members of her coalition. We identify four natural conditions on individuals’ preferences and show that, under each condition, stable (core) allocations exists.