Regression model with elliptically contoured errors

For the regression model y=X β+ε where the errors follow the elliptically contoured distribution, we consider the least squares, restricted least squares, preliminary test, Stein-type shrinkage and positive-rule shrinkage estimators for the regression parameters, β.

We compare the quadratic risks of the estimators to determine the relative dominance properties of the five estimators.     

Der Sequentieile Quotiententest bei irreduziblen homogenen Markovschen Ketten mit endlichem Zustandsraum

The Sequential Probaility Ratio Test is applied to test two simple hypotheses about the transition probability matrix of an irreducible homogeneous MARKOV chain with finite state space. An analogue (14) of Wald's Fundamental Identity, the Operating Characteristic Function (20-21) and the Average Sample Number (22-23) are given. These statements are generalizations of the MARKOV chain as well as some more conditions about the eigenvalues of the transition probability matrix.     

On the type-B integral equation and the distribution of wilks statist for testing independence of several groups of variables

In this paper, WILKS'type-B integral equation is solved in the general form of a series of beta functions and a series of weighted gamma functions as proposed by WALD and BROOKNER 1941. The coefficients in both representations can be obtained by explicit recurrence relartions, therefore the results solve many distributional problems and have the fewest computational difficulties of any representation that has surfaced to date. The radius of convergence of the second series representation is given, whereas the convergence property of the first series representation is given, whereas the convergence property of the first series representation was studied by WALD and Brookner. The exact null distributions of WILKS' statistic A for testing the independence of several groups of variables and of V = -log A are given. The coefficients in all the series representration can be computed recursilvely and hence can be obtained easily with the help of modern computatinal facilities     

Quasi-optimal Bayesian procedures of many hypotheses testing

Quasi-optimal procedures of testing many hypotheses are described in this paper. They significantly simplify the Bayesian algorithms of hypothesis testing and computation of the risk function. The relations allowing for obtaining the estimations for the values of average risks in optimum tasks are given. The obtained general solutions are reduced to concrete formulae for a multivariate normal distribution of probabilities. The methods of approximate computation of the risk functions in Bayesian tasks of testing many hypotheses are offered. The properties and interrelations of the developed methods and algorithms are investigated. On the basis of a simulation, the validity of the obtained results and conclusions drawn is presented.     

An Adaptive Test for the Two-Sample Location Problem Based on U-Statistics

For the two-sample location problem with continuous data we consider a general class of tests, all members of it are based on U-statistics. The asymptotic efficacies are investigated in detail. We construct an adaptive test where all statistics involved are suitably chosen U-statistics. It is shown that the proposed adaptive test has good asymptotic and finite sample power properties.     

The roles of supply network centralities in firm performance and the moderating effects of reputation and export-orientation

Abstract

This study explores how supply network degree, closeness, and betweenness centralities affect firm performance, and the moderating effects of organizational reputation (measured by PageRank centrality) and export-orientation. The supply chain relationship empirical data are drawn from manufacturing and manufacturing service companies in Hong Kong, China. Social network analysis and moderated regression analysis were adopted to test the hypotheses for a sample of 814 focal firms with 3086 supply chain ties. The results indicate that in-degree and closeness centralities improve firm performance. Reputation is found to positively moderate the relationship between closeness and sales performance, but negatively moderates the relationship between betweenness and sales performance. Export-orientation has no effect on relationships. This study contributes to the literature by providing additional empirical evidence on the role of supply network position in firm performance. It also introduces PageRank centrality as a new measure of organizational reputation in a supply network.     

What you say,and how you say it: Preschoolers' growth in vocabulary and communication skills differentially predict kindergarten academic achievement and self‐regulation

The idea that language skills support school readiness, predicting later self‐regulation and academic success, is widely accepted. Although vocabulary is often emphasized in the developmental literature, the ability to use language appropriately in the classroom, or social communication skills, may also be critical. This article examined longitudinal contributions of children's vocabulary and social communication skills, from preschool to kindergarten, to kindergarten academic achievement (reading and math) and self‐regulation (executive functions and learning behaviors). Participants were 164 children (14% Latinx, 30% Black, 56% White; 57% girls) enrolled in Head Start programs. Results revealed that initial levels and growth in vocabulary and communication skills predicted better academic achievement. Social communication skills uniquely predicted self‐regulation, after accounting for vocabulary. We discuss potential mechanisms for these links and recommend that strategies to build social communication skills be incorporated in preschool interventions promoting school readiness.     

Young children's perceptions and beliefs about hypothetical shy,unsociable, and socially avoidant peers at school

The aim of this study was to explore young children's perceptions, beliefs, and anticipated outcomes about different types of social withdrawal (shyness, unsociability, social avoidance). Participants were N = 212 children (n = 110 boys) aged 2.55–6.37 years (M = 4.86, SD = 0.89) recruited from three preschools and kindergartens in Italy. Children were interviewed individually and asked about hypothetical peers displaying different types of social withdrawal (i.e., shy, unsociable, socially avoidant) and for comparison purposes, aggressive and socially competent behaviors were also assessed. Among the three vignettes depicting types of withdrawn children, children rated the hypothetical shy peer as having the highest social motivations, the unsociable peer as receiving the least sympathy from others, and the avoidant peer as being the least intelligent and least liked by the teacher. In addition, girls reported wanting to play more with the shy peer than boys, and kindergarteners reported a higher affiliative preference for all subtypes of socially withdrawn peers than preschoolers. These findings suggest that Italian young children have a quite sophisticated ability to differentiate among the different social motivations and emotions that may underlie social withdrawal.     

School choice's idealized premises and unfulfilled promises: How school markets simulate options,encourage decoupling and deception,and deepen disadvantages

In school choice systems, families choose among publicly funded schools, and schools compete for students and resources. Using neoinstitutionalist and relational inequality theories, our article reinterprets recent critical sociological and education research to show how such markets involve actors' enacting myths; these beliefs and their associated practices normalized white, privileged consumption as a basis for revamping public education as market exchanges between schools and families. Proponents argue that choice empowers individuals, focuses organizations on improving quality, and benefits society more broadly by reducing inequality and segregation. We argue that such school choice myths' excessive emphases on individual decision‐making and provider performance obscure the actual impacts of school choice systems upon people, organizations, and society. First, rather than enlarging alternatives that families can easily research, select, and (if needed) exit, school choice systems often simulate options, especially for disadvantaged populations. Second, rather than focusing schools' efforts on performance, innovation, and accountability, they can encourage organizational decoupling, homogeneity, and deception. Third, rather than reducing societal harms, they can deepen inequalities and alienation. Future research should examine both how markets are animated by bounded relationality—routines that enable them to form, maintain, and complete exchanges with organizations—and how activism can challenge marketization.