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It is now more than 25 years since this text was first published in 1993. It has become a classic reference, cited extensively in literature from researchers around the globe. It is gratifying to see its sustained and widespread use by clinicians, faculty, students, and researchers in a variety of fields including rehabilitation, medicine, public health, nursing, public policy, epidemiology, exercise physiology, and other disciplines concerned with healthcare. This edition will continue to serve this wide audience.

As I have approached each revision, I have been struck by how much the framework for research continues to evolve over time, and this edition is no different. It incorporates several important contemporary perspectives.

First, regardless of the role we play in healthcare, be it clinician, administrator, policy maker, or researcher, we all need to be critical consumers of evidence to inform decisions. This requires at least a basic understanding of principles of measurement, design, and analysis to enable reasonable and critical evaluation.

Second, the concept of evidence-based practice (EBP), although ubiquitous in healthcare discussion, must be understood in terms of its full purpose for clinical decision-making, relying not only on literature but also on clinical expertise, patient values, and environmental conditions. These considerations have influenced translational research and the need to address meaningful outcomes.

Third, today’s healthcare enterprise mandates attention to interprofessional collaboration. I have included examples throughout the book to illustrate various concepts. These are drawn from many different fields, with the intent that all examples have wide application. I believe this is a distinct advantage of this book, to underscore the importance of appreciating research within and beyond one’s own field.

And finally, the content will work for those who want to plan or implement research. Detailed examples are included for those who want more depth, both in the text as well as in online supplements.

These directions and priorities continue to define research philosophies that guide the conduct of clinical inquiry, the types of questions that are deemed important, and how they influence advances in measurement and analysis techniques.

The popular features of the book have not changed, such as its accessible tone, use of extensive clinical examples to illustrate applications of design and statistics, and careful logic in explanation of complex concepts. It remains a comprehensive text, meant to fulfill different needs at different times, serving as both an introduction and a reference as readers grow in their knowledge and experience. However, this fourth edition does represent a significant update in format, focus, and organization.

New and Updated

Perhaps most notable is the new design, intended to make the text more reader-friendly and engaging with full color. Tables and figures have a new look to facilitate interpretation. Starting with the book’s title, the emphasis on EBP is clear, including the Focus on Evidence and Case in Point features in each chapter that illustrate the direct application of concepts in the literature. Additional information is included in boxes to clarify content, emphasize key points, offer interesting background and historical context—and a few fun facts along the way. Commentaries build on important concepts. Online resources have also been expanded, with chapter supplements, access to data files, and materials for instructors and students.

Five new chapters have been included in this edition, focusing on translational research (Chapter 2), evidence-based practice (Chapter 5), health measurement scales (Chapter 12), clinical trials (Chapter 14), and qualitative research (Chapter 21). All of these address content that was covered in previous editions but with greater depth and application.

Many chapters also include new or updated content to address current clinical research issues. For example,

  • Examples provided throughout the book have been updated with more recent literature.

  • The stronger emphasis on EBP includes use of the PICO strategy to answer clinical questions as well as to generate research questions. The EBP emphasis reflects a comprehensive model that includes research evidence, clinical expertise, patient values, and clinical circumstances.

  • The chapter on searching the literature has been reorganized to provide stronger guidance in that process.

  • The chapter on ethical principles has been updated to reflect recent changes in regulations and definitions.

  • Measurement chapters provide a stronger emphasis on relative and absolute reliability, a broader context for construct validity, and extensive discussion on measuring change.

  • The chapter on health measurement scales focuses on construct validity and reliability for questionnaires that are used to measure function, quality of life, and personal characteristics that impact health. It includes expanded coverage of Rasch analysis.

  • Chapters on foundations of design cover contemporary issues related to clinical trials, such as translational research, efficacy and effectiveness, superiority and non-inferiority trials, pragmatic trials, N-of-1 trials, and implementation studies.

  • Content related to observational designs has increased emphasis on use of these designs for diagnosis and prognosis, as well as for evaluating causal relationships.

  • Qualitative research has a stronger presence throughout the book, including a new chapter that also addresses mixed methods. Although this coverage cannot substitute for a full reference on this topic, this content should facilitate reading and interpreting the literature, and will reinforce the relevance of qualitative research in a variety of contexts.

  • The International Classification of Functioning, Disability and Health (ICF) is used as a framework for terminology as part of understanding patient-oriented research.

  • Statistics chapters have added coverage of validity measures and regression and multivariate methods, such as exploratory and confirmatory factor analysis and structural equation modeling. Data files for all examples presented in tables can be accessed online.

  • Information on power, effect size, and sample size calculations are integrated with statistical procedures and illustrated in detail in chapter supplements. Some analyses are done using SPSS and others using G*Power.

  • The chapters on critical appraisal and dissemination include information on use of reporting guidelines for different types of studies.

  • The chapter on systematic reviews has been expanded to include more detail related to meta-analyses and now includes information on scoping reviews.

Organization

Although the overall organization of the book remains the same with content in five parts, some chapters have been rearranged to better reflect their role in the research process. Each section focuses on a different phase of that process.

  • Part 1- Foundations of Research and Evidence focuses on fundamental concepts that define the clinical research enterprise, such as types of research, frameworks of health, translational research, application of theory, ethical principles, how to frame clinical and research questions, literature search strategies, and the overarching structure of EBP for clinical decision-making. These chapters provide an overview of the research process that serves as a foundation for the rest of the text.

  • Part 2- Concepts of Measurement includes the basic premises of measurement for all types of data collection, including validity and reliability. The chapter on surveys has been relocated to this section to emphasize their role as data collection tools rather than a design. Fundamental concepts in the design of health measurement scales are presented.

  • Part 3- Designing Clinical Research includes content on descriptive, observational, and explanatory research, with extensive examples related to validity and application of these designs. These include a variety of clinical trial designs, single-subject designs, observational studies using cohort and case-control designs, and descriptive and qualitative studies.

  • Part 4- Analyzing Data presents the full scope of statistical content, starting with descriptive statistics and developing concepts through multivariate procedures. Parametric and nonparametric statistics are described for comparative, predictive, and descriptive studies, validity and reliability, studies of diagnostic tests, and epidemiology related to risk assessments. Information is presented from an intuitive perspective without emphasis on mathematical derivation or statistical notation. These chapters include a review of output using SPSS to illustrate how statistical results can be interpreted. Data files can also be accessed online for all analyses.

  • Part 5- Putting It All Together focuses on the aspects of research that incorporate all the principles of design and analysis that have been covered in preceding chapters. Chapter 35 describes guidelines for developing a research proposal. Chapter 36 addresses the process of critical appraisal for several types of studies. Chapter 37 provides an overview of methods for conducting and evaluating systematic reviews, meta-analyses, and scoping reviews. Finally, Chapter 38 presents a format for preparing and disseminating research through publications and presentations.

Appendix A includes reference tables for major statistical tests and additional tables are provided in Appendix A Online. Appendix B includes an algorithm for choosing a statistical procedure based on design and measurement considerations. Appendix C covers content related to management of quantitative data, including data transformation. The glossary, also available online, provides a handy reference to define terms, symbols, and common abbreviations.

No matter how many years I have engaged in research, I continue to learn about advances in design and analysis that set new directions and priorities for clinical inquiry. This edition is intended to strengthen our collective commitment to new knowledge, discovery and innovation, and implementation of evidence, as we strive to provide the most effective care. The process remains a challenge to all of us engaged in healthcare, and this text will always be a work in progress. I look forward to continuing to hear from colleagues across disciplines regarding how to make this volume most useful.

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