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341.
As known, the least-squares estimator of the slope of a univariate linear model sets to zero the covariance between the regression residuals and the values of the explanatory variable. To prevent the estimation process from being influenced by outliers, which can be theoretically modelled by a heavy-tailed distribution for the error term, one can substitute covariance with some robust measures of association, for example Kendall's tau in the popular Theil–Sen estimator. In a scarcely known Italian paper, Cifarelli [(1978), ‘La Stima del Coefficiente di Regressione Mediante l'Indice di Cograduazione di Gini’, Rivista di matematica per le scienze economiche e sociali, 1, 7–38. A translation into English is available at http://arxiv.org/abs/1411.4809 and will appear in Decisions in Economics and Finance] shows that a gain of efficiency can be obtained by using Gini's cograduation index instead of Kendall's tau. This paper introduces a new estimator, derived from another association measure recently proposed. Such a measure is strongly related to Gini's cograduation index, as they are both built to vanish in the general framework of indifference. The newly proposed estimator is shown to be unbiased and asymptotically normally distributed. Moreover, all considered estimators are compared via their asymptotic relative efficiency and a small simulation study. Finally, some indications about the performance of the considered estimators in the presence of contaminated normal data are provided. 相似文献
342.
Cell Phone Survey Feasibility in The U.S.: Sampling and Calling Cell Numbers Versus Landline Numbers 总被引:6,自引:6,他引:0
Brick J. Michael; Brick Pat D.; Dipko Sarah; Presser Stanley; Tucker Clyde; Yuan Yangyang 《Public opinion quarterly》2007,71(1):23-39
In 2004, we conducted a nationwide dual frame survey of landlineand cell phone numbers to evaluate the feasibility of includingcell phone numbers in a random digit dial telephone survey.Households with both landline and cell phones were eligiblefor selection in both samples. This article describes our designand data collection methods; compares the results from the twosamples (with an emphasis on operational characteristics); andpresents the outcomes of two experimental manipulations designedto improve the cell phone response rate. 相似文献
343.
A measurement model was analyzed to demonstrate a differential distribution and cumulative exposure to psychosocial risk and protective influences of adolescent drug use among ethnically-diverse adolescent samples. The sample included U.S.-born (US) Latino (N = 837), foreign-born (FB) Latino (N = 447), White (N = 632), and African American (N = 618) adolescent boys. Psychological Distress, Peer Drug Use, and Adolescent Drug Use were significantly positively correlated with Peer Drug Use and Adolescent Drug Use. In contrast, Family, School, law abidance, and guilt were significantly negatively correlated with Peer Drug Use and Adolescent Drug Use. Multiple group analyses indicated significant similarities and differences among US and FB Latinos, and Whites. Implications for early prevention, multi-level interventions, and suggestions for future research are discussed. 相似文献
344.
The ethical work of program evaluators is based on a covenant of honesty and transparency among stakeholders. Yet even under the most favorable evaluation conditions, threats to ethical standards exist and muddle that covenant. Unfortunately, ethical issues associated with different evaluation structures and contracting arrangements have received little attention in the evaluation research literature. This article focuses on the unintended ethical threats associated with multitiered evaluation contexts. After briefly reviewing the various frames through which evaluation theory and ethics are commonly viewed, we discuss ethical challenges associated with multitiered evaluation designs including examples drawn from our evaluation projects. The article concludes with specific findings and recommendations for evaluators, grantors, grantees, and researchers. 相似文献
345.
Neighbors C Lostutter TW Whiteside U Fossos N Walker DD Larimer ME 《Journal of gambling studies / co-sponsored by the National Council on Problem Gambling and Institute for the Study of Gambling and Commercial Gaming》2007,23(3):259-273
Two studies examined the relationships among injunctive norms and college student gambling. In study 1 we evaluated the accuracy
of perceptions of other students’ approval of gambling and the relationship between perceived approval and gambling behavior.
In study 2 we evaluated gambling behavior as a function of perceptions of approval of other students, friends, and family.
In study 1, which included 2524 college students, perceptions of other students’ approval of gambling were found to be overestimated
and were negatively associated with gambling behavior. The results of study 2, which included 565 college students, replicated the findings of
study 1 and revealed positive associations between gambling behavior and perceived approval of friends and family. Results highlight the complexity of
injunctive norms and the importance of considering the reference group (e.g., peers, friends, family members) in their evaluation.
Results also encourage caution in considering the incorporation of injunctive norms in prevention and intervention approaches. 相似文献
346.
Castel AD Reed G Davenport MG Harrison LH Blythe D 《Journal of American college health : J of ACH》2007,56(2):119-127
OBJECTIVE: Maryland became the first state to pass a vaccination law requiring college and university students living on campus to obtain a meningococcal vaccination or to sign a waiver refusing vaccination because college students are at increased risk for disease. The authors sought to identify how Maryland colleges addressed the law and determine whether schools were in full compliance. PARTICIPANTS: The authors surveyed 32 college/university administrators via a self-administered questionnaire. METHODS: The authors calculated vaccination and waiver rates and assessed compliance with the law overall and with specific law components. RESULTS: Among 28 participating schools, annual vaccination rates and waiver rates among students during 2000-2004 ranged from 66%-76% and 12%-17%, respectively. Two (7%) schools were compliant with all components of the law. CONCLUSIONS: Mandatory vaccination laws do not ensure compliance at the college and university level. Mandatory reporting, increased education, and collaboration between colleges and universities and public health agencies are needed. 相似文献
347.
Interpreting the intentions of internet predators:an examination of online predatory behavior 总被引:1,自引:0,他引:1
Marcum CD 《Journal of child sexual abuse》2007,16(4):99-114
348.
Smink JD 《New directions for youth development》2007,(116):35-48, 10
In the United States and around the rest of the world, there is a renewed focus on ensuring that schools are providing students with the skills necessary to compete in the global economy. High-quality summer learning programs are an ideal vehicle to help students gain content knowledge and develop innovative skills: they provide time for individual exploration and hands-on, experiential opportunities that can instill a lifelong love of learning that carries into the classroom and the workforce. 相似文献
349.
Proponents of the common factors movement in marriage and family therapy (MFT) suggest that, rather than specific models of therapy, elements common across models of therapy and common to the process of therapy itself are responsible for therapeutic change. This article-the second of two companion articles-reports on a study designed to further investigate common factors in couple therapy. We used grounded theory techniques to analyze data from interviews with MFT model developers Dr. Susan M. Johnson, Dr. Frank M. Dattilio, Dr. Richard C. Schwartz, former students of Dr. Johnson and Dr. Schwartz, and each of their clients who had been successful in couple therapy. This article reports model-independent variables, that is, general aspects of therapy that are not directly related to the therapist's model. Model-independent categories include client variables, therapist variables, the therapeutic alliance, therapeutic process, and expectancy and motivational factors, each with several subcategories. We also present a conceptual framework that outlines how model-dependent and model-independent common factors may interact to produce change. We discuss our findings and proposed framework in relation to the current common factors literature in psychology and MFT. We also discuss clinical, training, and research implications. 相似文献
350.
Communities across the nation have become increasingly concerned about inhalant use and use of harmful legal products among youth because of increasing prevalence rates and deleterious health consequences from abusing these products. The increasing concern of communities about inhaling and ingesting legal products has been coupled with increasing awareness and concern about ability of youth to access and abuse a variety of other legal retail products. There are few examples of scientifically designed community prevention projects that seek to reduce youth abuse of such legal products. This article describes a community prevention trial that is designed to reduce sales of inhalants and other harmful legal products to youth and demonstrates how the retailer component of the trial can be rigorously evaluated. It also shows how data from youth purchase attempts can complement survey data from retailers. 相似文献