A mixed model approach for intent-to-treat analysis in longitudinal clinical trials with missing values
A mixed model approach for intent-to-treat analysis in longitudinal clinical trials with missing values

Author: Hrishikesh Chakraborty

Publisher: RTI Press

Published: 2009-02-28

Total Pages: 12

ISBN-13:

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Missing values and dropouts are common issues in longitudinal studies in all areas of medicine and public health. Intent-to-treat (ITT) analysis has become a widely accepted method for the analysis of controlled clinical trials. In most controlled clinical trials, some patients do not complete their intended followup according to the protocol for a variety of reasons; this problem generates missing values. Missing values lead to concern and confusion in identifying the ITT population, which makes the data analysis more complex and challenging. No adequate strategy exists for ITT analyses of longitudinal controlled clinical trial data with missing values. Several ad hoc strategies for dealing with missing values for an ITT analysis are common in the practice of controlled clinical trials. We performed a detailed investigation based on simulation studies to develop recommendations for this situation. We compared sizes (type I errors) and power between some popular ad hoc approaches and the linear mixed model approach under different missing value scenarios. Our results suggest that, for studies with a high percentage of missing values, the mixed model approach without any ad hoc imputation is more powerful than other options.

Power Aware Design Methodologies
Power Aware Design Methodologies

Author: Massoud Pedram

Publisher: Springer Science & Business Media

Published: 2007-05-08

Total Pages: 533

ISBN-13: 0306481391

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Power Aware Design Methodologies was conceived as an effort to bring all aspects of power-aware design methodologies together in a single document. It covers several layers of the design hierarchy from technology, circuit logic, and architectural levels up to the system layer. It includes discussion of techniques and methodologies for improving the power efficiency of CMOS circuits (digital and analog), systems on chip, microelectronic systems, wirelessly networked systems of computational nodes and so on. In addition to providing an in-depth analysis of the sources of power dissipation in VLSI circuits and systems and the technology and design trends, this book provides a myriad of state-of-the-art approaches to power optimization and control. The different chapters of Power Aware Design Methodologies have been written by leading researchers and experts in their respective areas. Contributions are from both academia and industry. The contributors have reported the various technologies, methodologies, and techniques in such a way that they are understandable and useful.

Recent Advancements in Structural Equation Modeling (SEM): From Both Methodological and Application Perspectives
Recent Advancements in Structural Equation Modeling (SEM): From Both Methodological and Application Perspectives

Author: Oi-Man Kwok

Publisher: Frontiers Media SA

Published: 2019-02-08

Total Pages: 251

ISBN-13: 2889457435

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Structural equation modeling (SEM) is becoming the central and one of the most popular analytical tools in the social sciences. Many classical and modern statistical techniques such as regression analysis, path analysis, confirmatory factor analysis, and models with both measurement and structural components have been shown to fall under the umbrella of SEM. Thus, the flexibility of SEM makes it applicable to many research designs, including experimental and non-experimental data, cross-sectional and longitudinal data, and multiple-group and multilevel data. In this eBook, you will find 19 cutting-edge papers from the Research Topic: Recent Advancements in Structural Equation Modeling (SEM). These 19 papers cover a wide variety of topics related to SEM, including: (a) analysis of different types of data (from cross-sectional data with floor effects to complex survey data and longitudinal data); (b) measurement-related issues (from the development of new scale to the evaluation of person fit and new ways to test measurement invariance); and (c) technical advancement and software development. We hope that the readers will gain new perspectives and be able to apply some of the new techniques and models discussed in these 19 papers.

Computer Simulation Validation
Computer Simulation Validation

Author: Claus Beisbart

Publisher: Springer

Published: 2019-04-09

Total Pages: 1056

ISBN-13: 3319707663

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This unique volume introduces and discusses the methods of validating computer simulations in scientific research. The core concepts, strategies, and techniques of validation are explained by an international team of pre-eminent authorities, drawing on expertise from various fields ranging from engineering and the physical sciences to the social sciences and history. The work also offers new and original philosophical perspectives on the validation of simulations. Topics and features: introduces the fundamental concepts and principles related to the validation of computer simulations, and examines philosophical frameworks for thinking about validation; provides an overview of the various strategies and techniques available for validating simulations, as well as the preparatory steps that have to be taken prior to validation; describes commonly used reference points and mathematical frameworks applicable to simulation validation; reviews the legal prescriptions, and the administrative and procedural activities related to simulation validation; presents examples of best practice that demonstrate how methods of validation are applied in various disciplines and with different types of simulation models; covers important practical challenges faced by simulation scientists when applying validation methods and techniques; offers a selection of general philosophical reflections that explore the significance of validation from a broader perspective. This truly interdisciplinary handbook will appeal to a broad audience, from professional scientists spanning all natural and social sciences, to young scholars new to research with computer simulations. Philosophers of science, and methodologists seeking to increase their understanding of simulation validation, will also find much to benefit from in the text.

Cochrane Handbook for Systematic Reviews of Interventions
Cochrane Handbook for Systematic Reviews of Interventions

Author: Julian P. T. Higgins

Publisher: Wiley

Published: 2008-11-24

Total Pages: 672

ISBN-13: 9780470699515

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Healthcare providers, consumers, researchers and policy makers are inundated with unmanageable amounts of information, including evidence from healthcare research. It has become impossible for all to have the time and resources to find, appraise and interpret this evidence and incorporate it into healthcare decisions. Cochrane Reviews respond to this challenge by identifying, appraising and synthesizing research-based evidence and presenting it in a standardized format, published in The Cochrane Library (www.thecochranelibrary.com). The Cochrane Handbook for Systematic Reviews of Interventions contains methodological guidance for the preparation and maintenance of Cochrane intervention reviews. Written in a clear and accessible format, it is the essential manual for all those preparing, maintaining and reading Cochrane reviews. Many of the principles and methods described here are appropriate for systematic reviews applied to other types of research and to systematic reviews of interventions undertaken by others. It is hoped therefore that this book will be invaluable to all those who want to understand the role of systematic reviews, critically appraise published reviews or perform reviews themselves.

Empirical Asset Pricing
Empirical Asset Pricing

Author: Wayne Ferson

Publisher: MIT Press

Published: 2019-03-12

Total Pages: 497

ISBN-13: 0262039370

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An introduction to the theory and methods of empirical asset pricing, integrating classical foundations with recent developments. This book offers a comprehensive advanced introduction to asset pricing, the study of models for the prices and returns of various securities. The focus is empirical, emphasizing how the models relate to the data. The book offers a uniquely integrated treatment, combining classical foundations with more recent developments in the literature and relating some of the material to applications in investment management. It covers the theory of empirical asset pricing, the main empirical methods, and a range of applied topics. The book introduces the theory of empirical asset pricing through three main paradigms: mean variance analysis, stochastic discount factors, and beta pricing models. It describes empirical methods, beginning with the generalized method of moments (GMM) and viewing other methods as special cases of GMM; offers a comprehensive review of fund performance evaluation; and presents selected applied topics, including a substantial chapter on predictability in asset markets that covers predicting the level of returns, volatility and higher moments, and predicting cross-sectional differences in returns. Other chapters cover production-based asset pricing, long-run risk models, the Campbell-Shiller approximation, the debate on covariance versus characteristics, and the relation of volatility to the cross-section of stock returns. An extensive reference section captures the current state of the field. The book is intended for use by graduate students in finance and economics; it can also serve as a reference for professionals.

Discrete Choice Methods with Simulation
Discrete Choice Methods with Simulation

Author: Kenneth Train

Publisher: Cambridge University Press

Published: 2009-07-06

Total Pages: 399

ISBN-13: 0521766559

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This book describes the new generation of discrete choice methods, focusing on the many advances that are made possible by simulation. Researchers use these statistical methods to examine the choices that consumers, households, firms, and other agents make. Each of the major models is covered: logit, generalized extreme value, or GEV (including nested and cross-nested logits), probit, and mixed logit, plus a variety of specifications that build on these basics. Simulation-assisted estimation procedures are investigated and compared, including maximum stimulated likelihood, method of simulated moments, and method of simulated scores. Procedures for drawing from densities are described, including variance reduction techniques such as anithetics and Halton draws. Recent advances in Bayesian procedures are explored, including the use of the Metropolis-Hastings algorithm and its variant Gibbs sampling. The second edition adds chapters on endogeneity and expectation-maximization (EM) algorithms. No other book incorporates all these fields, which have arisen in the past 25 years. The procedures are applicable in many fields, including energy, transportation, environmental studies, health, labor, and marketing.

Long-Range Dependence and Self-Similarity
Long-Range Dependence and Self-Similarity

Author: Vladas Pipiras

Publisher: Cambridge University Press

Published: 2017-04-18

Total Pages: 693

ISBN-13: 1107039460

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A modern and rigorous introduction to long-range dependence and self-similarity, complemented by numerous more specialized up-to-date topics in this research area.

International Encyclopedia of Human Geography
International Encyclopedia of Human Geography

Author:

Publisher: Elsevier

Published: 2019-11-29

Total Pages: 7278

ISBN-13: 0081022964

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International Encyclopedia of Human Geography, Second Edition, Fourteen Volume Set embraces diversity by design and captures the ways in which humans share places and view differences based on gender, race, nationality, location and other factors—in other words, the things that make people and places different. Questions of, for example, politics, economics, race relations and migration are introduced and discussed through a geographical lens. This updated edition will assist readers in their research by providing factual information, historical perspectives, theoretical approaches, reviews of literature, and provocative topical discussions that will stimulate creative thinking. Presents the most up-to-date and comprehensive coverage on the topic of human geography Contains extensive scope and depth of coverage Emphasizes how geographers interact with, understand and contribute to problem-solving in the contemporary world Places an emphasis on how geography is relevant in a social and interdisciplinary context