Comparativa de análisis de imputación de datos faltantes con análisis de casos completos en pruebas diagnósticas PDF Download
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Author: Álvaro Planchuelo Gómez
Publisher:
ISBN:
Category :
Languages : es
Pages : 83
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Book Description
Author: Álvaro Planchuelo Gómez
Publisher:
ISBN:
Category :
Languages : es
Pages : 83
Get Book Here
Book Description
Author:
Publisher:
ISBN:
Category :
Languages : es
Pages :
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Book Description
RESUMEN Las actitudes, el conocimiento y las acciones generalmente se basan en muestras. Algunos basan sus conclusiones en muestras pequeñas y pocas veces toman en cuenta la magnitud de lo que se desconoce. Generalmente se carece de recursos para estudiar más de una parte del problema de interés que pudiera aumentar nuestro conocimiento. Algunas razones para el uso de las técnicas de muestreo son: costo reducido, mayor velocidad, mayor enfoque o perspectiva y mayor exactitud. La fusión de datos surge como una alternativa a la fuente única de datos frente a la necesidad de conseguir el máximo de información posible al menor costo. Tiene como objetivo combinar datos de diferentes fuentes para poder disponer de toda la información en un solo archivo, aunque artificial, con todas las variables de interés. Utiliza lo mejor de la información existente en un archivo para reconstruir la información ausente en otro archivo. Es una estimación estadística de los datos faltantes. Es un medio de limitar la recolección de datos, reconstruyendo la información faltante. No es un problema de análisis estadístico con datos faltantes en el cual se consideran los mecanismos que conducen a la ausencia de datos. En el caso de la fusión de datos, se presentan bloques completos de datos ausentes, en general, muestras independientes. La revisión bibliográfica ha permitido analizar el problema del análisis de datos faltantes como una aproximación al tema de la fusión de datos, considerando que la fusión de datos es un caso particular. En este caso, se está hablando de bloques de datos faltantes y en muchas ocasiones, datos faltantes por diseño. El objetivo de la fusión de datos es por lo tanto, el obtener un solo archivo que pueda ser analizado posteriormente con herramientas de minería de datos. La idea es estimar los valores de las variables no informadas (valores faltantes) a partir de un bloque de variables informadas correlacionadas con el bloque de variables a reconstituir (variables c.
Author:
Publisher:
ISBN:
Category :
Languages : es
Pages : 223
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Book Description
Existen diversas formas de tratar la no respuesta, así como diferentes procedimientos de imputación de los datos que faltan, utilizándose estos según las condiciones de la encuesta y los objetivos que se pretendan. En este trabajo se resumen los distintos métodos para evitar este problema en la fase de recogida de datos, así como durante las etapas de su procesamiento y análisis. La finalidad última de estos métodos es conseguir una matriz de datos lo más completa y precisa posible. Aún así, una vez realizada la recogida de datos, y llevaba a cabo la depuración, es muy frecuente encontrar faltas o errores en algunas entradas. Ante esta problemática, las posibles alternativas que se plantean son realizar un análisis de casos completos, utilizar algún procedimiento para imputar los datos que faltan o intentar construir estimadores de mayor precisión. El trabajo está centrado en la definición de estimadores indirectos eficientes en presencia de falta de respuesta parcial. Para los correspondientes estimadores de razón, diferencia y regresión se proponen dos alternativas para construir estimadores que incluyan todos los casos disponibles. Tras la propuesta de estos estimadores, se realiza un estudio de simulación utilizando cinco poblaciones de uso frecuente en la literatura de muestreo en poblaciones finitas. Por último, se recurre a su aplicación ponen de manifiesto el buen comportamiento de los estimadores propuestos, mostrando que todos ellos provocan disminuciones importantes en los correspondientes errores muestrales. Por tanto, la elección de estos estimadores conllevará estimaciones más precisas que permitirán reducir el tamaño de muestra necesario para conseguir un cierto error.
Author: Rachel Yehuda
Publisher: American Psychiatric Pub
ISBN: 9780880488167
Category : Medical
Languages : en
Pages : 282
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Book Description
Fattori di rischio dei disturbi da stress post-traumatico: demografici, ambientali, genetici, neurocognitivi, biologici.
Author:
Publisher: Academic Press
ISBN: 008053239X
Category : Science
Languages : en
Pages : 311
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Book Description
Computer access is the only way to retrieve up-to-date sequences and this book shows researchers puzzled by the maze of URLs, sites, and searches how to use internet technology to find and analyze genetic data. The book describes the different types of databases, how to use a specific database to find a sequence that you need, and how to analyze the data to compare it with your own work. The content also covers sequence phenotype, mutation, and genetic linkage databases; simple repetitive DNA sequences; gene feature identification; and prediction of structure and function of proteins from sequence information. This book will be invaluable to those starting a career in life sciences research as well as to established researchers wishing to make full use of available resources. - Describes a wide range of databases: DNA, RNA, protein, pathways, and gene expression - Enables readers to access the information they need from databases on the web - Includes a directory of URLs for easy reference - Invaluable for those starting a career in life sciences research and also for established researchers wishing to make full use of available resources
Author: J. David Lowell
Publisher: University of Arizona Press
ISBN: 1941451004
Category : Biography & Autobiography
Languages : en
Pages : 495
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Book Description
When seven-year-old Dave Lowell was camped out at his father’s mine in the hills of southern Arizona in 1935, he knew he had found his calling. “Life couldn’t get any better than this,” he recalls. “I didn’t know what science was, but wisps of scientific thought were already working into my plan.” So began the legendary career of the engineer, geologist, explorer, and international businessman whose life is recounted in his own words in this captivating book. An Arizona native with family roots in territorial times, Lowell grew from modest beginnings on a ranch near Nogales to become a major world figure in the fields of minerals, mining, and economic geology. He has personally discovered more copper than anyone in history and has developed multibillion-dollar gold and copper mines that have changed the economies of nations. And although he has consulted for corporations in the field of mining, he has largely operated as an independent agent and explorer, the architect of his own path and success. His life’s story unfolds in four stages: his early education in his field, on-the-job learning at sites in the United States and Mexico, development of exploration strategies, and finally, the launch of his own enterprises and companies. Recurring themes in Lowell’s life include the strict personal, ethical, and tactical policies he requires of his colleagues; his devotion to his family; and his distaste for being away from the field in a corporate office, even to this day. The magnitude of Lowell’s overall success is evident in his list of mine discoveries, as well as in his scientific achievements and the enormous respect his friends and colleagues have had for him throughout his lengthy career, which he continues to zealously pursue.
Author: Dànielle Nicole DeVoss
Publisher: Peter Lang Incorporated, International Academic Publishers
ISBN: 9781433125614
Category : Copyright
Languages : en
Pages : 0
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Book Description
The symbols, signs, and traces of copyright and related intellectual property laws that appear on everyday texts, objects, and artifacts have multiplied exponentially over the past 15 years. Digital spaces have revolutionized access to content and transformed the ways in which content is porous and malleable. In this volume, contributors focus on copyright as it relates to culture. The editors argue that what «counts» as property must be understood as shifting terrain deeply influenced by historical, economic, cultural, religious, and digital perspectives. Key themes addressed include issues of how: - Culture is framed, defined, and/or identified in conversations about intellectual property; - The humanities and other related disciplines are implicated in intellectual property issues; - The humanities will continue to rub up against copyright (e.g., issues of authorship, authorial agency, ownership of texts); - Different cultures and bodies of literature approach intellectual property, and how competing dynasties and marginalized voices exist beyond the dominant U.S. copyright paradigm. Offering a transnational and interdisciplinary perspective, Cultures of Copyright offers readers - scholars, researchers, practitioners, theorists, and others - key considerations to contemplate in terms of how we understand copyright's past and how we chart its futures.
Author: William W. Eaton
Publisher: Academic Press
ISBN:
Category : Medical
Languages : en
Pages : 416
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Book Description
Epidemiologic Field Methods in Psychiatry: The NIMH Epidemiologic Catchment Area Program focuses on the methodology employed in the National Institute of Mental Health (NIMH) Epidemiologic Catchment Area (ECA) Program. The selection first elaborates on the historical context, major objectives, and study design and sampling the household population. Topics include the development of the ECA program, DIS instrument, program design, general issues in sampling community resident populations, household and respondent eligibility, household and respondent selection, weighting, and variance estimation. The manuscript then examines institutional survey and the characteristics, training, and field work of interviewers. Discussions focus on the changing nature of institutions, value of the institutional component, institutions included in institutional stratum, interviewer recruitment and selection, demographic characteristic of interviewers, and field work. The publication ponders on nonresponse and nonresponse bias in the ECA surveys, data preparation, and proxy interview, as well as quality of proxy data, item nonresponse, editing and coding, data entry and data cleaning, understanding nonresponse, and assessment of evidence for nonresponse bias. The selection is a valuable source of information for psychiatrists and readers interested in the Epidemiologic Catchment Area (ECA) Program.
Author: Kristin Luker
Publisher: Univ of California Press
ISBN: 0520907922
Category : Social Science
Languages : en
Pages : 342
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Book Description
In this important study of the abortion controversy in the United States, Kristin Luker examines the issues, people, and beliefs on both sides of the abortion conflict. She draws data from twenty years of public documents and newspaper accounts, as well as over two hundred interviews with both pro-life and pro-choice activists. She argues that moral positions on abortion are intimately tied to views on sexual behavior, the care of children, family life, technology, and the importance of the individual.
Author: Wendy Harcourt
Publisher: Zed Books Ltd.
ISBN: 1848136188
Category : Political Science
Languages : en
Pages : 369
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Book Description
Body Politics in Development sets out to define body politics as a key political and mobilizing force for human rights in the last two decades. This passionate and engaging book reveals how once-tabooed issues, such as rape, gender-based violence, and sexual and reproductive rights, have emerged into the public arena as critical grounds of contention and struggle. Engaging in the latest feminist thinking and action, the book describes the struggles around body politics for people living in economic and socially vulnerable communities and covers a broad range of gender and development issues, including fundamentalism, sexualities and new technologies, from diverse viewpoints. The book's originality comes through the author's rich experience and engagement in feminist activism and global body politics and was winner of the 2010 FWSA Book Prize.
