Entering a New Peer Group in Ethnically and Linguistically Diverse Childcare Classrooms

This short‐term longitudinal study examined changes over time in social competence with peers as a function of child and classroom characteristics. One hundred and seventy ethnically diverse low‐income children, all new to their peer groups, entered childcare classrooms with heterogeneous entry policies and ethnic/racial compositions. We observed them with their teachers and peers at entry and again six months later. Observers rated aggressive, anxious/withdrawn, and prosocial behavior with peers and observed complexity of peer play. Children who lacked peers with a shared ethnic heritage and children who spoke a different language at home than the language most often used in the classrooms appeared to be struggling with peer interaction six months after entry into the peer group. Children who had a peer who shared their ethnic heritage and entered the most ethnically diverse classrooms increased their complex peer play more than other children.     

Data skeletons: simultaneous estimation of multiple quantiles for massive streaming datasets with applications to density estimation

We consider the problem of density estimation when the data is in the form of a continuous stream with no fixed length. In this setting, implementations of the usual methods of density estimation such as kernel density estimation are problematic. We propose a method of density estimation for massive datasets that is based upon taking the derivative of a smooth curve that has been fit through a set of quantile estimates. To achieve this, a low-storage, single-pass, sequential method is proposed for simultaneous estimation of multiple quantiles for massive datasets that form the basis of this method of density estimation. For comparison, we also consider a sequential kernel density estimator. The proposed methods are shown through simulation study to perform well and to have several distinct advantages over existing methods.     

Constrained allocation problems with single-peaked preferences: An axiomatic analysis

We introduce a new class of problems that contains two existing classes: allocation problems with single-peaked preferences and bankruptcy problems. On this class, we analyze the implications of well-known properties such as Pareto optimality, strategy-proofness, resource-monotonicity, no-envy, equal treatment of equals, and two new properties we introduce, hierarchical no-envy and independence of nonbinding constraints. Unlike earlier literature, we consider rules that allow free-disposability. We present characterizations of a rule we introduce on this domain. We relate this rule to well-known rules on the aforementioned subdomains. Based on this relation, we present a characterization of a well-known bankruptcy rule called the constrained equal awards rule. Received: 22 June 2000/Accepted: 21 March 2002 This paper is based on the first chapter of my Ph.D. thesis submitted to the University of Rochester. I wish to thank my advisor, William Thomson, for helpful comments and suggestions.     

Organizational Compatibility and Workplace Drug Testing: Modeling the Adoption of Innovative Social Control Practices

Few researchers have examined organizational variation in the adoption of workplace drug testing, but innovation theory suggests that adoption is more likely when it is compatible with an organization's values, previously introduced ideas, and needs. Using data from the 1997 National Employee Survey, this research models the effects of organizational compatibility, industry, and establishment size on the adoption of drug testing. The data reveal that compatibility, as measured by an organization's rules orientation, presence of an employee assistance program, and mechanization, is associated with the adoption of drug testing. As predicted, the adoption of drug testing varies across industries and by establishment size.     

Project Jump: Young People's Perspectives on a Sexual Health Drama Project for Hard to Reach Young People

This article explores the qualitative process findings from an evaluation of Project Jump — a sexual health drama project for hard to reach young people. Project Jump aimed to enable young people to consider their sexual behaviour and its impact and consequence on other people and themselves. The research aimed to capture the experiences and perceptions of young people's involvement in the project, particularly in relation to the use of drama as a medium for learning. Findings from young people demonstrate that drama can offer an important alternative to traditional health promotion in that young people articulated positive aspects of their involvement. These included enthusiastic participation, empowerment and sexual health skills acquisition. In addition, critical areas for consideration for policy‐makers and practitioners in employing a drama‐based approach particularly in relation to effective identification, engagement and ongoing follow‐up activity with vulnerable groups are highlighted. © 2006 University of the West of England. Journal compilation © 2006 National Children's Bureau.     

Joint tests of non-nested models and general error specifications

This paper is concerned with joint tests of non-nested models and simultaneous departures from homoskedasticity, serial independence and normality of the disturbance terms. Locally equivalent alternative models are used to construct joint tests since they provide a convenient way to incorporate more than one type of departure from the classical conditions. The joint tests represent a simple asymptotic solution to the “pre-testing” problem in the context of non-nested linear regression models. Our simulation results indicate that the proposed tests have good finite sample properties.     

Complex belief-desire reasoning in children

Previous research concerned with children's belief-desire psychology has examined the capacity to predict or interpret action on the basis of the implicit proposition that ‘when an actor desires a particular end and believes that a particular action will achieve that end, he or she will undertake that action’. The limitations of this formulation for understanding acts of omission are outlined and an elaborated version of belief-desire psychology introduced. This version holds that ‘when an actor desires a particular end and believes that a particular action will achieve that end, and when it is believed that there are no co-occurring outcomes of that action whose avoidance is desired more highly than is the originally conceived end, then the actor will undertake the action which will satisfy the original desire’. An experiment is reported which examines 4-, 5, and 7-year-olds' ability to predict story characters' actions on the basis of either their true or false beliefs concerning undesirable outcomes associated with the pursuit of a desired end. Children of all age-groups provided evidence of understanding the elaborated version of belief-desire psychology. However, a significant improvement was noted between the ages of 4 and 7 years in the ability to understand circumstances involving false beliefs.     

Portmanteau test for conditional heteroscedasticity, using ranks of squared residuals

Squared residual autocorrelations have been found useful in detecting departures from linearity in time series models. This is especially the case with data exhibiting heterogeneity in variances. A rank test is proposed which is much more robust than its parametric counterpart.