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141.
Youth development does not take place only in institutions or even primarily in institutions. It takes place in the core economy-the economy of family, neighborhood, and community. Major challenges include rebuilding the kind of village it takes to raise a child and enabling a child to be part of that rebuilding. Another challenge is to make sure that any external incentives that are provided to youth are linked to activities that build self-esteem and convey a definition of value that is different from that established by money and market price. This chapter provides an introduction to time banking and to coproduction, approaches to youth development that enable youth to participate as major players, as opposed to recipients, in the reshaping of their lives and communities.  相似文献   
142.
Wilks’ ratio statistic can be defined in terms of the ratio of the sample generalized variances of two non-independent estimators of the same covariance matrix. Recently this statistic has been proposed as a control statistic for monitoring changes in the covariance matrix of a multivariate normal process in a Phase II situation, particularly when the dimension is larger than the sample size. In this article we derive a technique for decomposing Wilks’ ratio statistic into the product of independent factors that can be associated with the components of the covariance matrix. With these results, we demonstrate that, when a signal is detected in a control procedure for the Phase II monitoring of process variability using the ratio statistic, the signaling value can be decomposed and the process variables contributing to the signal can be specifically identified.  相似文献   
143.
A control procedure is presented in this article that is based on jointly using two separate control statistics in the detection and interpretation of signals in a multivariate normal process. The procedure detects the following three situations: (i) a mean vector shift without a shift in the covariance matrix; (ii) a shift in process variation (covariance matrix) without a mean vector shift; and (iii) both a simultaneous shift in the mean vector and covariance matrix as the result of a change in the parameters of some key process variables. It is shown that, following the occurrence of a signal on either of the separate control charts, the values from both of the corresponding signaling statistics can be decomposed into interpretable elements. Viewing the two decompositions together helps one to specifically identify the individual components and associated variables that are being affected. These components may include individual means or variances of the process variables as well as the correlations between or among variables. An industrial data set is used to illustrate the procedure.  相似文献   
144.
Many goodness of fit tests for bivariate normality are not rigorous procedures because the distributions of the proposed statistics are unknown or too difficult to manipulate. Two familiar examples are the ring test and the line test. In both tests the statistic utilized generally is approximated by a chi-square distribution rather than compared to its known beta distribution. These two procedures are re-examined and re-evaluated in this paper. It is shown that the chi-square approximation can be too conservative and can lead to unnecessary

rejection of normality.  相似文献   
145.
In reliability studies, one typically would assume a lifetime distribution for the units under study and then carry out the required analysis. One popular choice for the lifetime distribution is the family of two-parameter Weibull distributions (with scale and shape parameters) which, through a logarithmic transformation, can be transformed to the family of two-parameter extreme value distributions (with location and scale parameters). In carrying out a parametric analysis of this type, it is highly desirable to be able to test the validity of such a model assumption. A basic tool that is useful for this purpose is a quantile–quantile (QQ) plot, but in its use, the issue of the choice of plotting position arises. Here, by adopting the optimal plotting points based on Pitman closeness criterion proposed recently by Balakrishnan et al. (2010b Balakrishnan , N. , Davies , K. F. , Keating , J. P. , Mason , R. L. ( 2010b ). Computation of optimal plotting points based on Pitman Closeness with an application to goodness of fit for location-scale families. Submitted to Computational Statistics & Data Analysis.  [Google Scholar]), and referred to as simultaneous closeness probability (SCP) plotting points, we propose a correlation-type goodness of fit test for the extreme value distribution. We compute the SCP plotting points for various sample sizes and use them to determine the mean, standard deviation and critical values for the proposed correlation-type test statistic. Using these critical values, we carry out a power study, similar to the one carried out by Kinnison (1989 Kinnison , R. ( 1989 ). Correlation coefficient goodness of fit test for extreme value distribution . The American Statistician 43 : 98100 .[Taylor & Francis Online], [Web of Science ®] [Google Scholar]), through which we demonstrate that the use of SCP plotting points results in better power than with the use of mean ranks as plotting points and nearly the same power as with the use of median ranks. We then demonstrate the use of the SCP plotting points and the associated correlation-type test for Weibull analysis with an illustrative example. Finally, for the sake of comparison, we also adapt two statistics proposed by Gan and Koehler (1990 Gan , F. F. , Koehler , K. J. ( 1990 ). Goodness of fit based on P-P probability plots . Technometrics 32 : 289303 .[Taylor & Francis Online], [Web of Science ®] [Google Scholar]), in the context of probability–probability (PP) plots, based on SCP plotting points and compare their performance to those based on mean ranks. The empirical study also reveals that the tests from the QQ plot have better power than those from the PP plot.  相似文献   
146.
abstract

An array of browser extensions has been developed to help researchers locate full-text content, whether that full text is available in an institutional repository, on a publishers site, or in an open access journal. Examples of such browser extensions include Unpaywall, Kopernio, EZproxy tools, and Lean Library. This Balance Point column focuses on the growth of browser extensions, the need they are filling, and their adoption by libraries. Particular attention is paid to the Lean Library browser extension and the services offered by Lean Library. Drawing on the literature and interviews with librarians in the field, the advantages and disadvantages of browser extensions are addressed, as well as security concerns.  相似文献   
147.
This study presents a novel exploration into how people with dyslexia construct personal identities within anonymous, unsolicited, postings to an online discussion forum. An interpretational phenomenological analysis suggested three key identities: learning-disabled, differently-enabled and societally-disabled. These are discussed in terms of the extent to which they draw differentially on a discourse of disability as opposed to one of individual difference. The identities are to an extent malleable and overlapping according to context. Postings suggested overall that while some contributors constructed themselves as differently-enabled and celebrated dyslexia-related abilities, others sensed themselves having a disabled identity imposed upon them. Dyslexia is perceived as negatively construed within a society which promotes literacy and cognitive acuity as essential aspects of educational and social competence and where learning differences are poorly tolerated. In addition, this study highlights the potential of online forum contributions in the study of social influences in under-researched groups.  相似文献   
148.
Research has shown that pregnancy and motherhood increase the risk of experiencing intimate partner violence (IPV) — physical, sexual and emotional — in relationships. Much of this research, however, explores this issue in relation to adults and little attention has been given to the experiences of pregnant teenagers or teenage mothers in violent relationships. This paper focuses on three main areas to explore this, disadvantage, sexual negotiations and stigma, and draws upon interviews conducted by the authors with 16 teenage mothers in the UK as part of a wider study about IPV in the relationships of disadvantaged young people.  相似文献   
149.
ABSTRACT

The shift in the technology landscape has altered the technology ecosystem of adolescents and emerging adults in the 21st century. Yet, with greater use of digital gadgets comes greater mental health risks that technological advancement brings. This study provides a narrative review of contemporary cyber risks faced by adolescents and emerging adults. In particular, this review will cover dangers and effects of cyber-bullying, social media, cyber-dating violence, sextortion, sexting, revenge porn, online dating, catfishing, and scammers, with an emphasis to raise awareness and encourage proactive efforts dedicated to address these social concerns as the digital era continues to evolve.  相似文献   
150.
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