National Academies Press: OpenBook

Closing Evidence Gaps in Clinical Prevention (2022)

Chapter:Front Matter

Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Closing Evidence Gaps in Clinical Prevention. Washington, DC: The National Academies Press. doi: 10.17226/26351.
×

Closing
Evidence Gaps in
Clinical Prevention

Alexis Wojtowicz, Kathleen Stratton, and Tracy A. Lieu, Editors

Committee on Addressing Evidence Gaps in
Clinical Prevention Recommendations

Board on Population Health and Public Health Practice

Health and Medicine Division

A Consensus Study Report of

images

THE NATIONAL ACADEMIES PRESS
Washington, DC
www.nap.edu

Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Closing Evidence Gaps in Clinical Prevention. Washington, DC: The National Academies Press. doi: 10.17226/26351.
×

THE NATIONAL ACADEMIES PRESS 500 Fifth Street, NW Washington, DC 20001

This activity was supported with federal funds from the Agency for Healthcare Research and Quality and the National Institutes of Health, U.S. Department of Health and Human Services, Contract/Task Order No. HHSN263201800029I/75N 98020F00005. Any opinions, findings, conclusions, or recommendations expressed in this publication do not necessarily reflect the views of any organization or agency that provided support for the project.

International Standard Book Number-13: 978-0-309-26957-5
International Standard Book Number-10: 0-309-26957-1
Digital Object Identifier: https://doi.org/10.17226/26351
Library of Congress Catalog Number: 2021951344

Additional copies of this publication are available from the National Academies Press, 500 Fifth Street, NW, Keck 360, Washington, DC 20001; (800) 624-6242 or (202) 334-3313; http://www.nap.edu.

Copyright 2022 by the National Academy of Sciences. All rights reserved.

Printed in the United States of America

Suggested citation: National Academies of Sciences, Engineering, and Medicine. 2022. Closing evidence gaps in clinical prevention. Washington, DC: The National Academies Press. https://doi.org/10.17226/26351.

Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Closing Evidence Gaps in Clinical Prevention. Washington, DC: The National Academies Press. doi: 10.17226/26351.
×

Image

The National Academy of Sciences was established in 1863 by an Act of Congress, signed by President Lincoln, as a private, nongovernmental institution to advise the nation on issues related to science and technology. Members are elected by their peers for outstanding contributions to research. Dr. Marcia McNutt is president.

The National Academy of Engineering was established in 1964 under the charter of the National Academy of Sciences to bring the practices of engineering to advising the nation. Members are elected by their peers for extraordinary contributions to engineering. Dr. John L. Anderson is president.

The National Academy of Medicine (formerly the Institute of Medicine) was established in 1970 under the charter of the National Academy of Sciences to advise the nation on medical and health issues. Members are elected by their peers for distinguished contributions to medicine and health. Dr. Victor J. Dzau is president.

The three Academies work together as the National Academies of Sciences, Engineering, and Medicine to provide independent, objective analysis and advice to the nation and conduct other activities to solve complex problems and inform public policy decisions. The National Academies also encourage education and research, recognize outstanding contributions to knowledge, and increase public understanding in matters of science, engineering, and medicine.

Learn more about the National Academies of Sciences, Engineering, and Medicine at www.nationalacademies.org.

Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Closing Evidence Gaps in Clinical Prevention. Washington, DC: The National Academies Press. doi: 10.17226/26351.
×

Image

Consensus Study Reports published by the National Academies of Sciences, Engineering, and Medicine document the evidence-based consensus on the study’s statement of task by an authoring committee of experts. Reports typically include findings, conclusions, and recommendations based on information gathered by the committee and the committee’s deliberations. Each report has been subjected to a rigorous and independent peer-review process and it represents the position of the National Academies on the statement of task.

Proceedings published by the National Academies of Sciences, Engineering, and Medicine chronicle the presentations and discussions at a workshop, symposium, or other event convened by the National Academies. The statements and opinions contained in proceedings are those of the participants and are not endorsed by other participants, the planning committee, or the National Academies.

For information about other products and activities of the National Academies, please visit www.nationalacademies.org/about/whatwedo.

Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Closing Evidence Gaps in Clinical Prevention. Washington, DC: The National Academies Press. doi: 10.17226/26351.
×

COMMITTEE ON ADDRESSING EVIDENCE GAPS IN CLINICAL PREVENTION RECOMMENDATIONS

TRACY A. LIEU (Chair), Director of the Division of Research, Kaiser Permanente Northern California

CATHY J. BRADLEY, Professor and Associate Dean for Research, Colorado School of Public Health; Deputy Director, University of Colorado Cancer Center

THEODORE G. GANIATS, Professor Emeritus, Department of Family Medicine and Public Health, University of California, San Diego, School of Medicine

KENG-YEN HUANG, Associate Professor, Departments of Population Health and Child & Adolescent Psychiatry, New York University Grossman School of Medicine

PREETI GOKAL KOCHAR, Technical Information Specialist, National Library of Medicine, National Institutes of Health

ANN E. KURTH, Dean and Linda Koch Lorimer Professor of Nursing, Yale School of Nursing; Professor of Epidemiology of Microbial Diseases, Yale School of Public Health

TIANJING LI, Associate Professor, Department of Ophthalmology, University of Colorado School of Medicine

K. M. VENKAT NARAYAN, Director, Emory Global Diabetes Research Center; Ruth and O.C. Hubert Chair of Global Health and Professor of Epidemiology, Rollins School of Public Health; Professor of Medicine, Emory University School of Medicine

WANDA K. NICHOLSON, Professor, Department of General Obstetrics & Gynecology and Director, Diabetes and Obesity Core Center for Women’s Health Research, University of North Carolina School of Medicine

ELIZABETH O. OFILI, Professor of Medicine, Morehouse School of Medicine; Chief Medical Officer, Morehouse Choice Accountable Care Organization

NICOLAAS P. PRONK, President and Chief Science Officer, HealthPartners Institute

ROBERT B. WALLACE, Irene Ensminger Stecher Professor Emeritus of Epidemiology and Internal Medicine, University of Iowa College of Public Health

Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Closing Evidence Gaps in Clinical Prevention. Washington, DC: The National Academies Press. doi: 10.17226/26351.
×

Study Staff

KATHLEEN R. STRATTON, Study Director

ALEXIS WOJTOWICZ, Associate Program Officer

AYSHIA COLETRANE, Senior Program Assistant

REBECCA MORGAN, Senior Librarian

MISRAK DABI, Finance Business Partner

ROSE MARIE MARTINEZ, Senior Board Director

Science Writer

ROBERT POOL

Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Closing Evidence Gaps in Clinical Prevention. Washington, DC: The National Academies Press. doi: 10.17226/26351.
×

Reviewers

This Consensus Study Report was reviewed in draft form by individuals chosen for their diverse perspectives and technical expertise. The purpose of this independent review is to provide candid and critical comments that will assist the National Academies of Sciences, Engineering, and Medicine in making each published report as sound as possible and to ensure that it meets the institutional standards for quality, objectivity, evidence, and responsiveness to the study charge. The review comments and draft manuscript remain confidential to protect the integrity of the deliberative process.

We thank the following individuals for their review of this report:

Page viii Cite
Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Closing Evidence Gaps in Clinical Prevention. Washington, DC: The National Academies Press. doi: 10.17226/26351.
×

Although the reviewers listed above provided many constructive comments and suggestions, they were not asked to endorse the content of the report nor did they see the final draft before its release. The review of this report was overseen by BOBBIE BERKOWITZ, Columbia University, and JACK EBELER, Health Policy Alternatives, Inc. They were responsible for making certain that an independent examination of this report was carried out in accordance with standards of the National Academies and that all review comments were carefully considered. Responsibility for the final content rests entirely with the authoring committee and the National Academies.

Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Closing Evidence Gaps in Clinical Prevention. Washington, DC: The National Academies Press. doi: 10.17226/26351.
×

Preface

Preventing suffering and loss of life through early identification and treatment of individuals at risk is a central purpose of clinical care. For decades, primary care clinicians and others have relied on recommendations of the U.S. Preventive Services Task Force (USPSTF) in these efforts. The USPSTF’s careful reliance on evidence from rigorous studies to inform its statements has often highlighted topics and questions for which the evidence is insufficient to make a definitive recommendation. In an ideal world, when an insufficient evidence statement is rendered, research sponsors and researchers should quickly initiate high-quality studies needed to fill the most important evidence gaps. However, in some cases the lack of a widely agreed-on framework for describing and categorizing such evidence gaps has hampered efficient communication and progress.

The present study focused on developing a taxonomy to characterize evidence gaps in clinical prevention, and identifying research strategies and funding approaches to enable sponsors and researchers to more effectively fill these gaps. This work was sponsored by leaders in the National Institutes of Health (NIH) and the Agency for Healthcare Research and Quality (AHRQ), which supports the USPSTF. We are grateful to David Murray and Carrie Klabunde of the Office of Disease Prevention, NIH, and to Arlene Bierman and Amanda Borsky of the Center for Evidence and Practice Improvement, AHRQ, for their guidance and support. We also wish to acknowledge the important contributions of Susan Curry, who was instrumental in launching this effort.

Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Closing Evidence Gaps in Clinical Prevention. Washington, DC: The National Academies Press. doi: 10.17226/26351.
×

Our study committee approached this task with a sense of significance and optimism, and demonstrated intellectual generosity and graciousness throughout this multidisciplinary process. The committee and the Health and Medicine Division’s (HMD’s) staff of the National Academies developed this report and the taxonomy in an iterative manner, based on reviews of existing USPSTF recommendation statements and public meetings with experts from NIH, AHRQ, and other key organizations that sponsor research or support guideline committees, USPSTF members, and the research community. During this process we were particularly attuned to the fact that both the USPSTF and research sponsors must balance competing priorities among the many evidence gaps that could be addressed. As a former member of the USPSTF, the past chair of an NIH grant review committee, and a leader of a research department in a health care delivery system, I greatly appreciated the ability of our committee members and expert key informants to think pragmatically about how to facilitate communication and collaboration by the multiple stakeholders needed to successfully address evidence gaps.

We appreciate the education offered us by the speakers at our public meetings, including the following:

  • David Atkins, M.D., M.P.H., Director, Health Services Research & Development, U.S. Department of Veterans Affairs
  • Arlene Bierman, M.D., M.S., Director, Center for Evidence and Practice Improvement, AHRQ
  • Amanda Borsky, Dr.P.H., M.P.P., Program Manager, USPSTF, AHRQ
  • Sarabeth Broder-Fingert, M.D., M.P.H., Associate Professor of Pediatrics, Boston University School of Medicine; Co-Director, Innovation in Autism Disparities, Inclusion, Outreach, and Transition Services Lab, Boston University
  • Ned Calonge, M.D., M.P.H., President and Chief Executive Officer, Colorado Trust; Associate Professor of Family Medicine, Colorado School of Medicine, and Associate Professor of Epidemiology, Colorado School of Public Health, University of Colorado Denver
  • Doug Corley, M.D., Ph.D., Lead Investigator, National Cancer Institute (NCI) Population-based Research to Optimize the Screening Process Consortium; Research Scientist, Kaiser Permanente Northern California Division of Research
  • Susan Curry, Ph.D., Senior Advisor for Preventive Services, NIH; Dean Emerita and Distinguished Professor of Health Management and Policy, University of Iowa
Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Closing Evidence Gaps in Clinical Prevention. Washington, DC: The National Academies Press. doi: 10.17226/26351.
×
  • Paul Doria-Rose, Ph.D., D.V.M., Chief, Healthcare Assessment Research Branch, Health Delivery Research Program, Division of Cancer Control & Population Sciences, NCI
  • Chyke Doubeni, M.D., M.P.H., Member, USPSTF; Director, Mayo Clinic Center for Health Equity and Community Engagement Research
  • Carrie Klabunde, Ph.D., Senior Advisor for Disease Prevention, Office of Disease Prevention, NIH
  • Alex Krist, M.D., M.P.H., Immediate Past Chair, USPSTF; Professor of Family Medicine and Population Health, Virginia Commonwealth University
  • Amy Lansky, Ph.D., M.P.H., Director, Centers for Disease Control and Prevention Community Guide
  • Michael Lauer, M.D., Deputy Director, Extramural Research, NIH
  • Alan Leshner, Ph.D., Chief Executive Officer Emeritus, American Association for the Advancement of Science; Executive Publisher, Science; Former Director, National Institute on Drug Abuse, NIH; Former Deputy Director and Acting Director, National Institute of Mental Health (NIMH), NIH
  • Carol Mangione, M.D., M.S.P.H., FACP, Vice-Chair, USPSTF; Chief, Division of General Medicine & Health Services Research, University of California, Los Angeles (UCLA); Barbara A. Levey & Gerald S. Levey Professor of Medicine and Public Health, UCLA
  • David Murray, Ph.D., Associate Director for Prevention and Director, Office of Disease Prevention, NIH
  • Karen Robinson, Ph.D., M.Sc., Director, Evidence-based Practice Center, Johns Hopkins University
  • Michael Silverstein, M.D., M.P.H., Member, USPSTF; Professor of Pediatrics, Director, Division of General Academic Pediatrics, and Vice Chair, Research for the Department of Pediatrics, Boston University School of Medicine
  • Harold (Hal) Sox, M.D., Director, Peer Review, Patient-Centered Outcomes Research Institute
  • Ann Wagner, Ph.D., National Autism Coordinator, Office of NIMH Director, NIMH, NIH

We are also grateful to Caitlin Phelps (American College of Obstetricians and Gynecologists), Joe Selby, Steve Teutsch, and Gregory Traversy (Public Health Agency of Canada) for their helpful observations and suggestions.

The committee’s work would not have been possible without the insightful leadership of our study director Kathleen Stratton and the thoughtful and analytic contributions of Associate Program Officer Alexis

Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Closing Evidence Gaps in Clinical Prevention. Washington, DC: The National Academies Press. doi: 10.17226/26351.
×

Wojtowicz. We benefited from the excellent organizational skills of Ayshia Coletrane and the lucid writing assistance of Robert Pool as we crafted this report. We extend thanks to Rose Marie Martinez for her farsighted guidance and to the National Academies’ Research Center staff and many other staff members within HMD and the National Academies for their support.

The committee hopes this study will facilitate a common understanding of the key concepts related to evidence gaps in clinical prevention, support thoughtful discussion of priorities among multiple stakeholders, and lead to research that enhances clinical prevention in the years ahead.

Tracy A. Lieu, Chair
Committee on Addressing Evidence Gaps in Clinical Prevention Recommendations

Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Closing Evidence Gaps in Clinical Prevention. Washington, DC: The National Academies Press. doi: 10.17226/26351.
×

3-1 2020 I statement survey summary

4-1 Generic analytic framework for screenings

4-2 Generic analytic framework for behavioral interventions

4-3 Analytic framework for screenings and interventions to prevent dental caries in children younger than age 5

4-4 Analytic framework for preventing HIV infection with PrEP

4-5 The workflow for identifying evidence gaps in clinical prevention with the taxonomy

4-6 The workflow with foundational evidence gaps facet

4-7 The workflow with analytic framework evidence gaps facet

4-8 The workflow with dissemination and implementation evidence gaps facet

4-9 The workflow with prioritization criteria facet

4-10 The workflow with study specifications facet

5-1 The committee vision for improving clinical prevention research

TABLES

2-1 Matrix of Assessing Certainty and Magnitude of Net Benefit Used by the U.S. Preventive Services Task Force

2-2 Types of Evidence Gaps That May Lead to an I Statement for a Topic

3-1 Frequently Used Funding Mechanisms at the National Institutes of Health

3-2 Comparison of Grants and Contracts

3-3 National Institutes of Health Activity Related to I Statements

4-1 Foundational Evidence Gaps in the Cognitive Impairment Recommendation

4-2 Analytic Framework Gaps in the Cognitive Impairment Recommendation

4-3 Dissemination and Implementation Evidence Gaps in the Cognitive Impairment Recommendation

4-4 Foundational Evidence Gaps in the Atrial Fibrillation Recommendation

4-5 Analytic Framework Evidence Gaps in the Atrial Fibrillation Recommendation

4-6 Dissemination and Implementation Evidence Gaps in the Atrial Fibrillation Recommendation

Page xvii Cite
Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Closing Evidence Gaps in Clinical Prevention. Washington, DC: The National Academies Press. doi: 10.17226/26351.
×

Acronyms and Abbreviations

AAA abdominal aortic aneurysm
ACA Patient Protection and Affordable Care Act
ACE angiotensin-converting enzyme
AHCPR Agency for Healthcare Policy and Research
AHRQ Agency for Healthcare Research and Quality
ASD autism spectrum disorder
CDC Centers for Disease Control and Prevention
CDMRP Congressionally Directed Medical Research Program
CISNET Cancer Intervention and Surveillance Modeling Network
CPG clinical practice guideline
CPSTF Community Preventive Services Task Force
CT computed tomography
CTFPHE Canadian Task Force on the Public Health Examination
CTSA Clinical and Translational Science Awards
D&I dissemination and implementation
DOD U.S. Department of Defense
ECG electrocardiography
EPC Evidence-based Practice Center
Page xviii Cite
Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Closing Evidence Gaps in Clinical Prevention. Washington, DC: The National Academies Press. doi: 10.17226/26351.
×
FIT fecal immunochemical testing
FOA funding opportunity announcement
FY fiscal year
HHS U.S. Department of Health and Human Services
HMD Health and Medicine Division
HRSA Health Resources and Services Administration
IC institutes and centers
MCI mild cognitive impairment
NCI National Cancer Institute
NHLBI National Heart, Lung, and Blood Institute
NIH National Institutes of Health
NIMH National Institute of Mental Health
NOSI notice of special interest
ODP Office of Disease Prevention
PA program announcement
PCORI Patient-Centered Outcomes Research Institute
PICO population, intervention, comparison, outcomes
PICOTS population, intervention, comparison, outcome, timing, setting
PRC Prevention Research Center
PrEP preexposure prophylaxis
PROSPR Population-based Research to Optimize the Screening Process
RCT randomized controlled trial
RFA request for application
RFP request for proposal
SBIR Small Business Innovation Research
SBTT Small Business Technology Transfer
SPRINT Systolic Blood Pressure Intervention Trial
SVS Society for Vascular Surgery
UCLA University of California, Los Angeles
USPSTF U.S. Preventive Services Task Force
VA U.S. Department of Veterans Affairs
Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Closing Evidence Gaps in Clinical Prevention. Washington, DC: The National Academies Press. doi: 10.17226/26351.
×
PageR1
Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Closing Evidence Gaps in Clinical Prevention. Washington, DC: The National Academies Press. doi: 10.17226/26351.
×
PageR2
Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Closing Evidence Gaps in Clinical Prevention. Washington, DC: The National Academies Press. doi: 10.17226/26351.
×
PageR3
Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Closing Evidence Gaps in Clinical Prevention. Washington, DC: The National Academies Press. doi: 10.17226/26351.
×
PageR4
Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Closing Evidence Gaps in Clinical Prevention. Washington, DC: The National Academies Press. doi: 10.17226/26351.
×
PageR5
Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Closing Evidence Gaps in Clinical Prevention. Washington, DC: The National Academies Press. doi: 10.17226/26351.
×
PageR6
Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Closing Evidence Gaps in Clinical Prevention. Washington, DC: The National Academies Press. doi: 10.17226/26351.
×
PageR7
Page viii Cite
Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Closing Evidence Gaps in Clinical Prevention. Washington, DC: The National Academies Press. doi: 10.17226/26351.
×
PageR8
Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Closing Evidence Gaps in Clinical Prevention. Washington, DC: The National Academies Press. doi: 10.17226/26351.
×
PageR9
Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Closing Evidence Gaps in Clinical Prevention. Washington, DC: The National Academies Press. doi: 10.17226/26351.
×
PageR10
Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Closing Evidence Gaps in Clinical Prevention. Washington, DC: The National Academies Press. doi: 10.17226/26351.
×
PageR11
Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Closing Evidence Gaps in Clinical Prevention. Washington, DC: The National Academies Press. doi: 10.17226/26351.
×
PageR12
Page xiii Cite
Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Closing Evidence Gaps in Clinical Prevention. Washington, DC: The National Academies Press. doi: 10.17226/26351.
×
PageR13
Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Closing Evidence Gaps in Clinical Prevention. Washington, DC: The National Academies Press. doi: 10.17226/26351.
×
PageR14
Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Closing Evidence Gaps in Clinical Prevention. Washington, DC: The National Academies Press. doi: 10.17226/26351.
×
PageR15
Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Closing Evidence Gaps in Clinical Prevention. Washington, DC: The National Academies Press. doi: 10.17226/26351.
×
PageR16
Page xvii Cite
Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Closing Evidence Gaps in Clinical Prevention. Washington, DC: The National Academies Press. doi: 10.17226/26351.
×
PageR17
Page xviii Cite
Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2022. Closing Evidence Gaps in Clinical Prevention. Washington, DC: The National Academies Press. doi: 10.17226/26351.
×
PageR18
Next: Summary »
Closing Evidence Gaps in Clinical Prevention Get This Book
×
Buy Paperback | $55.00 Buy Ebook | $44.99
MyNAP members save 10% online.
Login or Register to save!
Download Free PDF

Closing Evidence Gaps in Clinical Prevention, a new consensus study report from the National Academies of Sciences, Engineering, and Medicine's Board on Population Health and Public Health Practice, evaluates evidence gaps in clinical prevention recommendations described by the United States Preventive Services Task Force and other clinical practice guideline developers and presents a taxonomy of these evidence gaps for future use. This report aims to improve the coordination of efforts to describe and communicate priority evidence gaps among funders and researchers. It also proposes new opportunities for collaboration among researchers, funders, and guideline developers to accelerate research that could close evidence gaps.

The authoring committee has also developed an interactive graphic that can be used as a workflow diagram for implementing the taxonomy. This workflow walks users through reviewing evidence, characterizing evidence gaps using relevant taxonomies, and developing a research agenda. Click here to view and engage with the interactive graphic.

  1. ×

    Welcome to OpenBook!

    You're looking at OpenBook, NAP.edu's online reading room since 1999. Based on feedback from you, our users, we've made some improvements that make it easier than ever to read thousands of publications on our website.

    Do you want to take a quick tour of the OpenBook's features?

    No Thanks Take a Tour »
  2. ×

    Show this book's table of contents, where you can jump to any chapter by name.

    « Back Next »
  3. ×

    ...or use these buttons to go back to the previous chapter or skip to the next one.

    « Back Next »
  4. ×

    Jump up to the previous page or down to the next one. Also, you can type in a page number and press Enter to go directly to that page in the book.

    « Back Next »
  5. ×

    Switch between the Original Pages, where you can read the report as it appeared in print, and Text Pages for the web version, where you can highlight and search the text.

    « Back Next »
  6. ×

    To search the entire text of this book, type in your search term here and press Enter.

    « Back Next »
  7. ×

    Share a link to this book page on your preferred social network or via email.

    « Back Next »
  8. ×

    View our suggested citation for this chapter.

    « Back Next »
  9. ×

    Ready to take your reading offline? Click here to buy this book in print or download it as a free PDF, if available.

    « Back Next »
Stay Connected!