Motor Function and Social Participation in Kindergarten Children

This study focused on the associations between individual variations in children’s motor abilities and individual differences in social participation and play behavior. Indoor and outdoor play behavior patterns of 88 kindergarten children were observed, and a battery of standard assessments of basic motor functions was administered. The findings indicate significant associations between children’s motor abilities and social and nonsocial forms of play. Results are discussed in relation to existing conceptual models of the underlying causes for nonsocial behavior.     

Competence-Based and Integrity-Based Trust as Predictors of Acceptance of Carbon Dioxide Capture and Storage (CCS)

Public trust in organizations that are involved in the management and use of new technologies affects lay judgments about the risks and benefits associated with these technologies. In turn, judgments about risks and benefits influence lay attitudes toward these technologies. The validity of this (indirect) effect of trust on lay attitudes toward new technologies, which is referred to as the causal chain account of trust, has up till now only been examined in correlational research. The two studies reported in this article used an experimental approach to more specifically test the causal chain account of trust in the context of carbon dioxide capture and storage technology (CCS). Complementing existing literature, the current studies explicitly distinguished between two different types of trust in organizations: competence-based trust (Study 1) and integrity-based trust (Study 2). In line with predictions, results showed that the organizational position regarding CCS implementation (pro versus con) more strongly affected people's risk and benefit perceptions and their subsequent acceptance of CCS when competence-based trust was high rather than low. In contrast, the organizational position had a greater impact on people's level of CCS acceptance when integrity-based trust was low rather than high.     

Negotiated Project Engagements: Learning from Experience

How far is it possible to capture the lessons tobe drawn from successive projects that involveintervention by social scientists within or betweenorganizations, whether acting as researchers, asconsultants, as agents of change, or in some combination ofthese roles? This paper outlines the way in which aframework was developed, by staff and associates of TheTavistock Institute, for examining the varied and often subtle influences of successive“negotiated project engagements” on thedevelopment of wider personal, institutional, anddisciplinary programs. This framework is designed totake into account the contrasting perspectives of the investigatorsthemselves, of their organizational hosts, and of anyexternal sponsors whose primary concern will normally bewith project outcomes at a more generalized level. As an illustration, particular reference ismade to the experience of a pioneering project concernedwith policy-making in city government. This project wasundertaken to advance the understanding and practice of public planning, while also exploring thepotential for synergy between the perspectives ofoperational research and applied social science. Thepaper concludes with some speculations about thepotential for further developing this kind of frameworkin supporting experiential learning.     

Out of the Limelight: Discredited Communities and Informal Communication on the Internet

In this article we will suggest that print and related traditional media have been used more successfully in constituting a public sphere than in supporting more private and localized forms of community building (Habermas 1989; Stone 1991). The costs and control of print media, in addition to the stability of the content, have reduced the applicability of these media to the improvisatory and quotidian social processes that groups use to help keep themselves cohesive. In contrast, computer-based interactions have been and are being used extensively to support many of the informal interactions and related activities necessary to communities, giving members new tools for negotiating and rehearsing public forms of group life (Jones 1995). We hope to show how the public aspirations and problems of social groups shape their encounters with computers and encourage them to use computer interaction to manage their public representations.     

Automated Pricing Rules in Electronic Posted Offer Markets

Internet markets are heralded as enhancing efficiency by providing buyers and sellers with an abundance of information. In these electronic markets, firms have the opportunity to employ "pricebots," computerized algorithms that automatically adjust prices to prevailing market conditions. This article uses laboratory methods to examine the potential market impact of the endogenous selection of three automated pricing algorithms: undercutting, low-price matching, and trigger pricing. We find that the undercutting algorithm leads to prices similar to the game-theoretic prediction. Low-price matching generates significantly higher prices, and trigger pricing results in market prices below the game-theoretic prediction.     

The efficient cross-validation of principal components applied to principal component regression

The cross-validation of principal components is a problem that occurs in many applications of statistics. The naive approach of omitting each observation in turn and repeating the principal component calculations is computationally costly. In this paper we present an efficient approach to leave-one-out cross-validation of principal components. This approach exploits the regular nature of leave-one-out principal component eigenvalue downdating. We derive influence statistics and consider the application to principal component regression.     

A simple approximation relation between the symmetric generalized logistic and the students t distributions

In this paper, we obtain a new approximation of the Student's t distribution by using the symmetric generalized logistic (SGL) distribution function. The error of this approximation is shown to be 0(1/n² )where nis the degrees of freedom of thetdistribution. In comparison to similar approximations by George and Ojo and George et al. (1986), this new approximation is much simpler and more accurate. It is also shown that under some conditions, the tdistribution is a good approximation of the SGL distribution. Therefore, the complicated expressions for the cumulants and moments of the SGL can be approximated by those of the t, distribution. Finally, numerical results are given.     

Modern Food Supply Chains and Development: Evidence from Horticulture Export Sectors in Sub‐Saharan Africa

The global food system is undergoing rapid processes of transformation and modernisation. This is causing important changes in developing‐country food supply chains, particularly in supermarket‐driven and high‐value export chains, but the welfare implications of these changes are poorly understood. This article analyses and compares the welfare effects in different horticulture export chains in sub‐Saharan Africa, disentangling different types of effects and the channels through which rural households are affected. Its main conclusion is that increased high‐value exports and the modernisation of export supply chains can bring about important positive welfare effects, which can occur in various ways through product‐ or labour‐market effects and through direct and indirect effects.