Uniform strong convergence results for the conditional kaplan-meier estimator and its quantiles

We consider a fixed design model in which the responses are possibly right censored. The aim of this paper is to establish some important almost sure convergence properties of the Kaplan-Meier type estimator for the lifetime distribution at a given covariate value. We also consider the corresponding quantile estimator and obtain a modulus of continuity result. Our rates of uniform strong convergence are obtained via exponential probability bounds.     

Solitary‐functional Play and Solitary‐pretend Play: Another Look at the Construct of Solitary‐active Behavior Using Playground Observations

Although the construct of solitary‐active behavior calls for the aggregation of solitary‐functional play and solitary‐pretend play, there is little empirical support for combining them into one construct. Furthermore, little work has been done in early childhood to examine these behaviors on the playground. The purpose of this study was to observe children's behavior on the playground to explore whether solitary‐functional and solitary‐pretend behaviors are related to one another and to other indices of social adjustment/maladjustment. Examining a sample of 361 preschoolers, results revealed that (1) solitary‐functional and solitary‐pretend play were not related, (2) solitary‐functional play was associated with solitary‐passive and reticent behaviors, as well as less social play, co‐operative rough and tumble play, sociable/friendliness, assertiveness, and lower peer acceptance, and (3) solitary‐pretend play was linked to lower peer acceptance and more social maladjustment, including venting, reactive aggression (but not proactive aggression), active exclusion, victimization, and being distractible.     

The Internationalization of Educational and Vocational Guidance

The authors identify and discuss the main themes from the discourse on the internationalization of educational and vocational guidance at the 2004 Symposium on International Perspectives on Career Development, cosponsored by the International Association for Educational and Vocational Guidance and the National Career Development Association. Participants from 46 countries discussed international perspectives on and comparative features of educational and vocational guidance. They concentrated on issues of designing and adapting models, methods, and materials for career education and counseling. Three additional themes revolved around the importance of public policy initiatives, training enough practitioners to meet the growing international need for career services, and the promise of information technology for expanding the delivery of educational and vocational guidance and for supporting career counselors.     

Socially Structured Games

We generalize the concept of a cooperative non-transferable utility game by introducing a socially structured game. In a socially structured game every coalition of players can organize themselves according to one or more internal organizations to generate payoffs. Each admissible internal organization on a coalition yields a set of payoffs attainable by the members of this coalition. The strengths of the players within an internal organization depend on the structure of the internal organization and are represented by an exogenously given power vector. More powerful players have the power to take away payoffs of the less powerful players as long as those latter players are not able to guarantee their payoffs by forming a different internal organization within some coalition in which they have more power. We introduce the socially stable core as a solution concept that contains those payoffs that are both stable in an economic sense, i.e., belong to the core of the underlying cooperative game, and stable in a social sense, i.e., payoffs are sustained by a collection of internal organizations of coalitions for which power is distributed over all players in a balanced way. The socially stable core is a subset and therefore a refinement of the core. We show by means of examples that in many cases the socially stable core is a very small subset of the core. We will state conditions for which the socially stable core is non-empty. In order to derive this result, we formulate a new intersection theorem that generalizes the KKMS intersection theorem. We also discuss the relationship between social stability and the wellknown concept of balancedness for NTU-games, a sufficient condition for non-emptiness of the core. In particular we give an example of a socially structured game that satisfies social stability and therefore has a non-empty core, but whose induced NTU-game does not satisfy balancedness in the general sense of Billera.      

Searching for critical issues in philanthropy

Who Really Cares: America's Charity Divide—Who Gives, Who Doesn't, and Why It Matters, by Arthur C. Brooks. New York: Basic Books, 2006. 256 pp., $26.00 cloth, $16.95 paper. Foundations and Public Policy: The Mask of Pluralism, by Joan Roelofs. Albany: State University of New York Press, 2003. 270 pp., $29.95 paper. The Foundation: A Great American Secret, by Joel Fleishman. New York: PublicAffairs, 2007. 384 pp., $27.95 cloth. The Billionaire Who Wasn't: How Chuck Feeney Secretly Made and Gave Away a Fortune, by Conor O'Clery. New York: PublicAffairs, 2007. 352 pp., $26.95 cloth.     

Government policies and private enterprise—Some fundamental trends

In this article the author argues that governmental policies depend largely on the objectives of the community, more specifically with regard to private enterprises it may be interesting to reflect on the respective roles of the free market mechanism, the public authorities and the socio-economic groups in the future economic system.     

The Domain and Interpretation of Utility Functions: An Exploration

This paper proposes an exploration of the methodology of utility functions that distinguishes interpretation from representation. While representation univocally assigns numbers to the entities of the domain of utility functions, interpretation relates these entities with empirically observable objects of choice. This allows us to make explicit the standard interpretation of utility functions which assumes that two objects have the same utility if and only if the individual is indifferent among them. We explore the underlying assumptions of such an hypothesis and propose a non-standard interpretation according to which objects of choice have a well-defined utility although individuals may vary in the way they treat these objects in a specific context. We provide examples of such a methodological approach that may explain some reversal of preferences and suggest possible mathematical formulations for further research. This revised version was published online in June 2006 with corrections to the Cover Date.     

Uncertainties in the CIIT Model for Formaldehyde-Induced Carcinogenicity in the Rat: A Limited Sensitivity Analysis–I

Scientists at the CIIT Centers for Health Research (Conolly et al., 2000, 2003; Kimbell et al., 2001a, 2001b) developed a two-stage clonal expansion model of formaldehyde-induced nasal cancers in the F344 rat that made extensive use of mechanistic information. An inference of their modeling approach was that formaldehyde-induced tumorigenicity could be optimally explained without the role of formaldehyde's mutagenic action. In this article, we examine the strength of this result and modify select features to examine the sensitivity of the predicted dose response to select assumptions. We implement solutions to the two-stage cancer model that are valid for nonhomogeneous models (i.e., models with time-dependent parameters), thus accounting for time dependence in variables. In this reimplementation, we examine the sensitivity of model predictions to pooling historical and concurrent control data, and to lumping sacrificed animals in which tumors were discovered incidentally with those in which death was caused by the tumors. We found the CIIT model results were not significantly altered with the nonhomogeneous solutions. Dose-response predictions below the range of exposures where tumors occurred in the bioassays were highly sensitive to the choice of control data. In the range of exposures where tumors were observed, the model attributed up to 74% of the added tumor probability to formaldehyde's mutagenic action when our reanalysis restricted the use of the National Toxicology Program (NTP) historical control data to only those obtained from inhalation exposures. Model results were insensitive to hourly or daily temporal variations in DNA protein cross-link (DPX) concentration, a surrogate for the dose-metric linked to formaldehyde-induced mutations, prompting us to utilize weekly averages for this quantity. Various other biological and mathematical uncertainties in the model have been retained unmodified in this analysis. These include model specification of initiated cell division and death rates, and uncertainty and variability in the dose response for cell replication rates, issues that will be considered in a future paper.