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201.
k-POD: A Method for k-Means Clustering of Missing Data 总被引:1,自引:0,他引:1
The k-means algorithm is often used in clustering applications but its usage requires a complete data matrix. Missing data, however, are common in many applications. Mainstream approaches to clustering missing data reduce the missing data problem to a complete data formulation through either deletion or imputation but these solutions may incur significant costs. Our k-POD method presents a simple extension of k-means clustering for missing data that works even when the missingness mechanism is unknown, when external information is unavailable, and when there is significant missingness in the data.[Received November 2014. Revised August 2015.] 相似文献
202.
203.
AbstractTo increase the effectiveness and efficiency of searches for information, accounting students, researchers, practitioners, and regulators could benefit from a Website devoted to the electronic access to journals. The site described here addresses such a need in the business discipline of accounting. On the site, the titles of over 470 journals are listed and categorized by topical areas within accounting. Then, within each accounting category, the journals are grouped according to their Internet accessibility. To provide the user with quick access to the various journals, the site provides links to the homepages of the various journals. Serials Review 2002; 28:201–205. 相似文献
204.
Karin Braunsberger Richard O. Flamm 《Voluntas: International Journal of Voluntary and Nonprofit Organizations》2013,24(1):1-31
Universities in the U.S. have been criticized for not contributing enough to the social well-being of the communities within which they operate, and business schools have been accused of failing to prepare students adequately for careers in business. These criticisms have led to increased focus on service learning, a form of experiential learning that aids students in the application of theoretical knowledge to “real-life” situations—including problems and opportunities—faced by local as well as international communities. Even though service-learning has become fairly popular in business schools throughout the U.S., there is relatively little literature that illuminates its application. Thus, the present article describes a service-learning project in a marketing research course and how this project supports the university’s mission of civic engagement. Included are also a discussion of course-specific objectives as well as learning goals, objectives, and assessments as commonly required by regional and national accreditation agencies. 相似文献
205.
Preston H. Brown Dini M. Miller Carlyle C. Brewster Richard D. Fell 《Urban Ecosystems》2013,16(2):193-216
The distribution of ant colonies within a community is often well defined, yet this distribution can change due to changing environmental conditions, resource availability, and colony growth. In this study, structure infesting ant communities were sampled for one year within three Puerto Rican housing developments of different ages. These developments represented environments in different stages of recovery after a disturbance (secondary succession). Spatial mapping was used to plot the distribution and abundance of ant communities within these developments. At the beginning of the study, the youngest housing development (1 year since construction), had the fewest number of species present (ave. 1.6 per house). The second housing development (4 years old) had a greater number of species (ave. 2.6 per house), and a greater sampling frequency (the same species collected at multiple houses) than Site 1. The oldest development (8 years old) had both the greatest number of species (ave. 2.7 per house), and sampling frequency of the three sites. In all developments, the number of species, sampling frequency, and ant biomass increased throughout the year as colonies grew and foraging ranges expanded. It was observed in all developments, that species coexistence also increased throughout the year. As colony populations increased, there was a greater occurrence of multiple species being collected at the same sample house. In the youngest development, the two most dominant species increased in numbers during the year and began to be collected from the same sample houses. Spatial diagrams documented that multiple species in the older housing developments (later stages of succession), also shared a common distribution. Even the most dominant species (S. invicta) in all three sites, did not exclude additional species from foraging within its established range. 相似文献
206.
Richard Reinoehl ACSW Constance Hoenk Shapiro Ph.D. ACSW 《Journal of Social Work Education》2013,49(3):61-67
Abstract The merging of videodiscs and computers now makes possible a variety of exciting instructional strategies in education. This article highlights the ways in which videodiscs can be utilized to individualize the pace of student learning and to enhance the transfer of new learning from the classroom to beginning professional encounters. Ranging from concept learning to simulations of client-worker interactions, the application of videodisc technology to classroom instruction enables the blending of theory and practice so valued by social work educators. 相似文献
207.
Richard Albrecht 《?sterreichische Zeitschrift für Soziologie》2011,36(3):109-112
208.
Richard Bach Jensen 《Social history》2013,38(2):281-283
Noel W. Thompson, The People's Science (1984), viii+252 (Cambridge University Press, £22.50). R. J. P.Kain and H. C. Prince, The Tithe Surveys of England and Wales (1985), xvi‐+327 (Cambridge University Press, £27.50). John Breuilly and Wieland Sachse, Joachim Friedrich Martens (1860–1877) und die Deutsche Arbeiterbewegung (1984), 489 (Schwartz, Göttingen, DM 43.00). (Joachim Friedrich Martens and the German Labour Movement) Anthony D. King, The Bungalow. The Production of a Global Culture (1984), xvii+310 (Routledge and Kegan Paul, £35.00). A. J. A. Morris, The Scaremongers. The Advocacy oj War and Rearmament 1896–1914 (1984), xi+495 (Routledge &; Kegan Paul, £25.00). L'Archéologie industrielle en France (C.I.L.A.C., 48 rue Saint Lambert, 75015 Paris, 440 FF per issue). 相似文献
209.
The spread of the international AIDS pandemic has drawn attention to the urgent need for data on human sexual behavior; yet the lack of an established tradition of theory and method in sex research has limited the development of research initiatives in this area. This has been particularly true in the study of homosexual and bisexual behavior, which has relied heavily on the use of quantitative survey methods that largely fail to address cross‐cultural differences in the structure and meaning of same‐sex sexual experience. More qualitative approaches offer the possibility of investigating homosexual and bisexual behavior within a broader social and cultural context and can therefore play an important role in developing a framework for the comparative analysis of behavioral data. This article seeks to contribute to the development of theory and method in sex research by outlining key research issues and possible methodologies for the qualitative investigation of homosexual and bisexual behavior in relation to HIV/AIDS. 相似文献
210.
Amélie Desvars-Larrive Mario Baldi Theresa Walter Richard Zink Chris Walzer 《Urban Ecosystems》2018,21(5):951-964
Nowadays, the majority of human beings live in urban ecosystems, with this proportion expected to continue increasing in the future. With the growing importance of urban rat-associated issues (e.g. damages to urban infrastructures, costs of rat-control programs, rat-associated health risks), it is becoming indispensable to fill the identified gaps in knowledge on the urban brown rat regarding, among others, its density, home range, genetic structure, and infectious status. In this context, live-trapping is a crucial prerequisite to any scientific investigation. This paper assesses the main constraints and challenges regarding the urban field and describes the major steps to be considered when planning research on urban rats. The primary challenges are i) the characterization of the urban experimental unit; ii) the choice of a trapping design: the use of live-trapping in capture-mark-recapture design, in association with modern statistics, is highly recommended to answer ecological questions (although these methods, mostly developed in natural ecosystems, need to be implemented for the urban field); iii) the potential ethical considerations with regard to animal welfare and field-worker safety; iv) the building of mutually-beneficial collaborations with city stakeholders, pest control professionals, and citizens. Emphasis must be put on communication to the public and education of field-workers. One major need of modern urban rat research is a peer-validated field methodology allowing reproducibility, repeatability, and inference from urban field studies and enabling researchers to answer long-standing key questions about urban rat ecology. 相似文献