排序方式: 共有29条查询结果,搜索用时 109 毫秒
1.
Kimberly F. Sellers Derek S. Young 《Journal of Statistical Computation and Simulation》2019,89(9):1649-1673
While excess zeros are often thought to cause data over-dispersion (i.e. when the variance exceeds the mean), this implication is not absolute. One should instead consider a flexible class of distributions that can address data dispersion along with excess zeros. This work develops a zero-inflated sum-of-Conway-Maxwell-Poissons (ZISCMP) regression as a flexible analysis tool to model count data that express significant data dispersion and contain excess zeros. This class of models contains several special case zero-inflated regressions, including zero-inflated Poisson (ZIP), zero-inflated negative binomial (ZINB), zero-inflated binomial (ZIB), and the zero-inflated Conway-Maxwell-Poisson (ZICMP). Through simulated and real data examples, we demonstrate class flexibility and usefulness. We further utilize it to analyze shark species data from Australia's Great Barrier Reef to assess the environmental impact of human action on the number of various species of sharks. 相似文献
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Sellers RM Caldwell CH Schmeelk-Cone KH Zimmerman MA 《Journal of health and social behavior》2003,44(3):302-317
This study examines the direct and indirect relationships among racial identity, racial discrimination, perceived stress, and psychological distress in a sample of 555 African American young adults. A prospective study design was used to assess the influence of two dimensions of racial identity attitudes (i.e., centrality and public regard) on other study variables to investigate the relationship between racial identity attitudes and psychological distress. The results show some evidence of a direct relationship between racial centrality and psychological distress, as well as evidence of indirect relationships for both centrality and public regard through the impact of racial discrimination and perceived stress. In addition, racial centrality was both a risk factor for experiencing discrimination and a protective factor in buffering the negative impact of discrimination on psychological distress. Results are discussed within the context of identifying multiple pathways to psychological well-being for African American young adults within the context of racial discrimination. 相似文献
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J Sellers 《Second opinion (Park Ridge, Ill.)》1989,(12):46-61
Medical ethics is viewed as one phase of the human rights movement begun by blacks in the 1950s and then continued by feminists, consumerists, and bioethicists. 相似文献
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The Gang Resistance Education and Training (G.R.E.A.T.) program is a school-based gang prevention initiative developed in 1991 through the collaborative efforts of the Bureau of Alcohol, Tobacco, and Firearms, the Federal Law Enforcement Training Center, and the Phoenix Police Department. Uniformed law enforcement officers, certified as G.R.E.A.T. instructors, teach the 9-week curriculum to middle students. In 1994, the National Institute of Justice funded a national evaluation of the G.R.E.A.T. program. The process evaluation component of this larger study is reported. First, results of on-site observations of the G.R.E.A.T. Officer Training program, including an overview of the training activities, and the authors' assessment of the training process are reported. Second, observations of the implementation of the program by officers at six sites are reported. Of primary concern was whether the program delivered to students was similar to the program taught to the officers during the G.R.E.A.T. Officer Training. 相似文献
5.
Eleanor K. Seaton Cleopatra H. Caldwell Robert M. Sellers James S. Jackson 《Journal of research on adolescence》2010,20(3):774-788
The present study examined discrimination attributions in the psychological well‐being of Black adolescents. Findings are based on a representative sample of 810 African American and 360 Caribbean Black youth, aged 13–17, who participated in the National Survey of American Life. Youth completed measures of perceived discrimination, discrimination attributions, depressive symptoms, self‐esteem, and life satisfaction. Approximately half the youth attributed discrimination to race/ethnicity (43%), followed by age (17%), physical appearance (16.5%), and gender (7.5%), and there were no ethnic, gender, or age differences regarding discrimination attributions. Key findings suggest that the association between perceived discrimination and psychological well‐being did not vary according to discrimination attribution, which implies that discrimination is harmful for Black youth regardless of the attribution. 相似文献
6.
Wendy Sellers Campbell Idania Lisette Lainez Hernández Jessica Ceremuga Hallie Farmer 《Journal of Community Practice》2013,21(4):440-457
This study examines a Nicaraguan community 3 years after the signing of the Dominican Republic-Central American Free Trade Agreement (CAFTA). Qualitative and quantitative methods were used to learn how families, living in a community constructed near a US-owned factory, maintained resilience under growing negative conditions. These conditions relate to family dislocation, loss of support systems, lack of childcare, safe water, and food security, in addition to labor injustices. Although maintaining relatively high scores on a baseline resilience test, these families and others like them in Central America, demonstrate a struggle for survival in a globalized context. 相似文献
7.
McGraw SA Sellers DE Stone EJ Bebchuk J Edmundson EW Johnson CC Bachman KJ Luepker RV 《Evaluation review》1996,20(3):291-312
The purpose of this article is to illustrate the use of process evaluation for understanding study outcomes. Data from the Child and Adolescent Trial for Cardiovascular Health (CATCH), a large school-based field trial, are used. Teacher characteristics, measures of classroom curriculum implementation, and competing influences are linked to changes in dietary knowledge, intentions, and self-efficacy of students in the intervention schools. Multiple regression analyses indicate that teacher characteristics did not predict program implementation. Teacher characteristics and program fidelity, or the number of modifications made to the classroom curriculum during implementation, had direct and independent effects on student outcomes. 相似文献
8.
We study variations in the severity of the 1997 financial crisis in a sample of 25 developing countries. We use both currency depreciation and stock market returns as crisis measures. Our key findings are that countries that started 1997 with an exchange rate peg experienced significantly greater currency depreciation and significantly lower stock returns than would be predicted from the levels of various macroeconomic indicators. 相似文献
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The Poisson distribution is a benchmark for modeling count data. Its equidispersion constraint, however, does not accurately represent real data. Most real datasets express overdispersion; hence attention in the statistics community focuses on associated issues. More examples are surfacing, however, that display underdispersion, warranting the need to highlight this phenomenon and bring more attention to those models that can better describe such data structures. This work addresses various sources of data underdispersion and surveys several distributions that can model underdispersed data, comparing their performance on applied datasets. 相似文献