National Academies Press: OpenBook

A Smarter National Surveillance System for Occupational Safety and Health in the 21st Century (2018)

Chapter: 8 Next Steps for Improving Worker Safety and Health Through a Smarter Occupational Surveillance System

« Previous: 7 Key Actions to Move Forward with an Ideal National Occupational Safety and Health Surveillance System
Suggested Citation:"8 Next Steps for Improving Worker Safety and Health Through a Smarter Occupational Surveillance System." National Academies of Sciences, Engineering, and Medicine. 2018. A Smarter National Surveillance System for Occupational Safety and Health in the 21st Century. Washington, DC: The National Academies Press. doi: 10.17226/24835.
×
Page 164
Suggested Citation:"8 Next Steps for Improving Worker Safety and Health Through a Smarter Occupational Surveillance System." National Academies of Sciences, Engineering, and Medicine. 2018. A Smarter National Surveillance System for Occupational Safety and Health in the 21st Century. Washington, DC: The National Academies Press. doi: 10.17226/24835.
×
Page 165
Suggested Citation:"8 Next Steps for Improving Worker Safety and Health Through a Smarter Occupational Surveillance System." National Academies of Sciences, Engineering, and Medicine. 2018. A Smarter National Surveillance System for Occupational Safety and Health in the 21st Century. Washington, DC: The National Academies Press. doi: 10.17226/24835.
×
Page 166
Suggested Citation:"8 Next Steps for Improving Worker Safety and Health Through a Smarter Occupational Surveillance System." National Academies of Sciences, Engineering, and Medicine. 2018. A Smarter National Surveillance System for Occupational Safety and Health in the 21st Century. Washington, DC: The National Academies Press. doi: 10.17226/24835.
×
Page 167
Suggested Citation:"8 Next Steps for Improving Worker Safety and Health Through a Smarter Occupational Surveillance System." National Academies of Sciences, Engineering, and Medicine. 2018. A Smarter National Surveillance System for Occupational Safety and Health in the 21st Century. Washington, DC: The National Academies Press. doi: 10.17226/24835.
×
Page 168
Suggested Citation:"8 Next Steps for Improving Worker Safety and Health Through a Smarter Occupational Surveillance System." National Academies of Sciences, Engineering, and Medicine. 2018. A Smarter National Surveillance System for Occupational Safety and Health in the 21st Century. Washington, DC: The National Academies Press. doi: 10.17226/24835.
×
Page 169
Suggested Citation:"8 Next Steps for Improving Worker Safety and Health Through a Smarter Occupational Surveillance System." National Academies of Sciences, Engineering, and Medicine. 2018. A Smarter National Surveillance System for Occupational Safety and Health in the 21st Century. Washington, DC: The National Academies Press. doi: 10.17226/24835.
×
Page 170

Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

8 Next Steps for Improving Worker Safety and Health Through a Smarter Occupational Surveillance System The Occupational Safety and Health Act of 1970 sought “to assure so far as possible every working man and woman in the Nation safe and healthful working conditions and to preserve our human re- sources.” Progress toward this goal has been steady, but the human and economic toll from work injury and disease remains unacceptably high. Occupational health surveillance provides essential information necessary to understand the distribution and determinants of the burden of injury and disease among workers, to track changes in this burden over time, and to assess the impact and success of interventions designed to reduce or eliminate the adverse consequences of work across the full spectrum of employ- ment in the United States. Although there have been advances in OSH surveillance since the 1987 National Research Council report, greater advances can be made through the application of new technologies, systems approaches, and coordinated efforts. This final chapter collects the recommended components of an action plan to move toward a smarter and more dynamic OSH surveillance system. It begins by providing one final me- ta-recommendation that the committee considers essential to achieve a smarter system. Then, drawing on the recommendations made throughout the report that delineate near- and longer-term steps toward pro- gress in OSH surveillance, the chapter outlines the report’s call for four major categories of action. It ac- cordingly summarizes the committee’s recommendations thematically, rather than following their order of presentation in earlier chapters, with the four major categories as follows: Prioritize and coordinate OSH surveillance Improve data collection Expand biomedical informatics use and capabilities Strengthen data analysis and information dissemination for prevention The discussion refers to the recommendations by their letter designation, and the report provides a listing of the full set of recommendations in Appendix C, which cites them in the order of their presentation in the report. Readers may refer as needed to the individual recommendations by letter in Appendix C when they are cited in the remainder of this chapter. VISION FOR A SMARTER SYSTEM The committee’s vision for the future of OSH surveillance is a collaborative system of systems. Recognizing the varying mandates and roles of the many relevant stakeholders, the committee believes that it is possible to strengthen the ongoing coordination and data sharing across federal agencies, be- tween federal and state agencies, across state agencies (e.g., labor and health), and with employers and workers to result in the maximum possible engagement of all. A system of systems approach to OSH sur- veillance would minimize the undercounting of occupational injuries and illnesses by gathering sufficient data that include nontraditional occupations and worker groups in a representative manner and enhancing prevention-relevant information in surveillance data to include race and ethnicity as well as occupation and industry (general and detailed). It would expand outcomes to include chronic diseases and their caus- es and include leading indicators, primarily through adequately detailed exposure information. Further, the system of systems would maximize appropriate use of technologies to facilitate all surveillance pro- cesses and create structures to disseminate information to levels where it can be acted upon. 164 Prepublication Copy

Next Steps for Improving Worker Safety and Health Through a Smarter Occupational Surveillance System There are several critical enabling components that will be leveraged by the agencies responsible for implementing the smarter system. Such efforts begin by extending the capacities of the agencies through targeted enhancements of both existing systems and technical personnel, and through effective communi- cation across agencies. This will be complemented by information and other inputs available through em- ployers, employee representatives, relevant intermediaries, and individuals along with engaged health care systems, all taking full advantage of state-of-the-art technology. Engagement of employers and health care providers will result in substantive improvements by augmenting existing resources (e.g., effective collaboration with workers’ compensation systems, effi- cient implementation of electronic reporting, including occupational information in electronic health rec- ords) along with development of new resources such as voluntary within-industry partnerships to engage collectively in exposure surveillance (e.g., modeled on the Industrial Minerals Association silica exposure assessment in the European Union). At the same time a complementary effort at incorporating leading indicators of risk such as hazard and exposure surveillance will advance with better utilization of existing resources (e.g., OSHA compliance data and NIOSH Health Hazard Evaluation information) coupled with enhancements (e.g., collection of required exposure monitoring and industry-specific exposure surveys). Individuals, in their capacity as workers and beyond, will play an essential role in the smarter sys- tem through their participation in population health surveys that incorporate occupational information (e.g., household survey of nonfatal occupational injuries and illnesses [HSOII], the National Health Inter- view Survey, the Behavioral Risk Factor Surveillance System, and the Medical Expenditure Panel Sur- vey). Evolving health care systems, along with technology imbedded in the delivery system, will greatly facilitate enriched inputs on health and safety outcome data. Inclusion of occupational information in the electronic health record and advances in health care reporting structures will improve content and effi- ciency in collecting reports of work-related health conditions. Fundamental to a successful smarter system will be sufficient and creative use of information tech- nology capacity and resources. These will include effective autocoding of occupational information in all appropriate records, electronic reporting wherever possible from all traditional and emerging reporting sources, and development of hardware and software for efficient collection of information in real time (e.g., exposure and compliance data). To enable the system fully, methods and tools need to be developed for timely and effective collection and analysis of surveillance data. In addition, software needs to be de- signed and disseminated so that all relevant stakeholders can undertake their own examination of surveil- lance information so that they can act on findings as quickly as possible to improve health and safety for workers regardless of setting or context. The committee has based its analysis and recommendations on an understanding that desired im- provements in worker safety and health are more likely to be met when an adequate amount of infor- mation is available at a level of detail sufficient to facilitate effective public health actions. Producing this information requires coordination of agencies, with input from stakeholders, collection of data that can provide useful information on all components of the workforce, and the ability to process and share in- formation using modern technologies. Even as the committee recognizes that the pathway to achieve a smarter system is neither direct nor without challenging barriers, ultimately, all the elements are attainable in an effectively coordinated national system. ACTION STEPS – REPORT RECOMMENDATIONS This report provides recommendations for improved OSH surveillance, many of which offer both near- and long-term recommended actions. The near-term actions are intended to be possible even when recognizing the constraints on all actors that arise from currently limited resources and complicated his- torical precedents. The longer-term actions are expected to require new resources (financial and person- nel) along with the evolution of elements, some of which will be made possible by implementing shorter- term recommendations while others are beyond the direct control of the leadership for OSH surveillance.. Prepublication Copy 165

A Smarter National Surveillance System for Occupational Safety and Health in the 21st Century The details of the recommendations are provided throughout the report; the following synthesizes the recommended action steps in the four categories mentioned earlier. Prioritize and Coordinate OSH Surveillance First and foremost, surveillance for occupational health and safety needs to become a priority if it is to serve the core function of providing the information essential to guide public health actions to improve worker safety and health. The committee recognizes that surveillance often exists in the background of public health programs, rising to a level of importance only at times that call for emergency action. It is less well appreciated that, even in the background, the system needs to operate efficiently—seamlessly collecting, collating, and assessing information without interruption to support evidence-based actions, emergency or otherwise. With surveillance as a priority, the development of a centralized coordination of a system of systems can provide the essential evidence to guide prevention efforts that advance program objectives in the most cost-effective manner. Recommendation Q (meta-recommendation): The Secretary of Health and Human Services, with the support of the Secretary of Labor, should direct NIOSH to form and lead a coordinating entity in partnership with OSHA, BLS, and other relevant agencies. The coordinating entity should: develop and regularly update a national occupational safety and health surveillance strategic plan that is based on well-articulated objectives; coordinate the design and evaluation of an evolving national system of systems for OSH surveil- lance and for the dissemination of surveillance information provided by these systems; publish a report on progress toward the strategic plan’s implementation at least every 5 years, documenting advances toward achieving a 21st-century smarter occupational safety and health (OSH) surveillance system; and engage partners, including other federal health statistics agencies, state agencies with OSH re- sponsibilities, and stakeholders. This recommendation is arguably the cornerstone for the advice that the committee is offering. The envisioned coordinating entity is essential if there is to be a cross-agency vision and plan for moving for- ward, if the other recommendations are to be properly prioritized and carried out, and if the resulting sys- tem of systems is to be effectively guided by the principles described in Chapter 2. The evolving system needs to be robust and collaborative, with strong leadership, and needs to use consistent standards across all relevant domains. It needs to assure timely analysis and interpretation of surveillance inputs tied close- ly with dissemination to relevant actors. And it will need to safeguard privacy and confidentiality, moni- tor data quality to ensure program efficiency and impact, and be staffed by well-trained public health pro- fessionals with access to the tools and technology necessary to achieve surveillance objectives. The envisioned strategic plan would need to provide an overall vision and framework for OSH sur- veillance for the nation that government agencies and stakeholders will then implement. As a living doc- ument, the OSH surveillance strategic plan can be flexible to adjust to changing priorities, needs, and cir- cumstances. The plan is intended to provide a sustainable framework for accomplishing the core objectives of OSH surveillance: Guide immediate action to control threats to occupational health and safety; Measure the health and economic burden of work-related injuries or illnesses and monitor trends over time and space; Identify industries, occupations, and worksites as well as populations defined by sociodemo- graphic characteristics and work arrangements at high risk for work-related injury, illness, or haz- ardous exposures; 166 Prepublication Copy

Next Steps for Improving Worker Safety and Health Through a Smarter Occupational Surveillance System Detect and respond to new or emerging workplace hazards or facilitate the investigation of new diseases linked to occupational exposures; Guide the planning, implementation, and evaluation of programs and policies intended to prevent and control work-related injuries, illnesses, and hazardous workplace exposures; and Generate hypotheses and make pertinent data available for research. As a system of systems, this smarter system would need to begin by making clear the specific objec- tives for each of the surveillance systems within the overall system. It would include concrete objectives for each of the key federal agencies. It would also include a detailed plan for engagement of the state- based OSH programs that identifies priority conditions for expanded surveillance, provides guidance on how to use the data generated by the states, and, whenever possible, identifies the agencies (i.e., federal or state) that need to take the lead for these conditions. Resource needs need to be organized, projected, and articulated. Benchmarks need to be identified and realistic timelines need to be specified to keep attention on measurable progress. Furthermore, evaluation needs to be an essential element at all levels, organized so that successful systems can be expanded when possible and replicated at different levels of the organi- zation as appropriate. Systems that do not meet objectives or that cease to be cost effective can be termi- nated. In setting forth OHS surveillance as a national priority, the responsible agencies, most centrally NIOSH, will need to organize to make certain that there is a clear line of responsibility and authority over each agency’s OSH surveillance activities and personnel. Unless leadership structurally and distinctly recognizes and articulates these actions, the system will likely be incapable of achieving the identified goals. At the same time that those structural changes are being developed, the agencies need to ensure that links across agencies are as seamless as possible and that barriers to timely, efficient sharing of data and information are eliminated. As with most public health activities that address more than one priority, the overall system will need to be founded on a close working relationship between federal and state partners. Together, coordinated federal and state systems offer immense advantages over either operating inde- pendently. The report accordingly stresses the value of an effective federal-state partnership and strength- ened state efforts, both to facilitate and serve a coordinated national effort to identify and monitor priority conditions and emerging problems, and to foster prevention programs at the level that can best address these concerns (Recommendation C). The committee also notes that the most effective intervention activities will need to act on the causes and not the consequences of occupational health problems. Exposure and hazard surveillance points the way to primary prevention and is the most effective leading indicator available. Consequently, the com- mittee has proposed a sequence of efforts designed to construct a robust exposure component of the envi- sioned surveillance system. The report calls for an immediate collaborative effort of federal agencies to initiate the development of a comprehensive approach for exposure surveillance that builds and updates a database of risks and exposures to predict and locate work-related acute and chronic health conditions for prevention (Recommendation H). Emphasizing that the overall system relies, at all levels and in all circumstances, on an adequately educated and trained professional workforce, the report also calls for a collaborative federal effort to pro- mote and support education and training of the surveillance workforce. The responsible agencies need to identify core competencies required for OSH surveillance (e.g., epidemiology, biomedical informatics, and biostatistics) and engage educational institutions to establish or modify training programs accordingly (Recommendation P). Steps toward building this trained workforce are proposed that can begin immedi- ately. Improve Data Collection The committee began its effort by adopting the Centers for Disease Control and Prevention’s defini- tion of surveillance, which starts with the collection and processing of relevant data closely linked to analysis and interpretation that can guide policy and interventions. The committee accordingly focused on Prepublication Copy 167

A Smarter National Surveillance System for Occupational Safety and Health in the 21st Century the sources and quality of the inputs to the smarter system. Throughout the report, the issue of under- counting of occupational injuries and illnesses is highlighted from two perspectives: cases that are out of scope or cases that are simply unreported. Failure to count occupational injuries that are out of scope is a recognized consequence of surveys or other assessments that do not capture data on some segments of the working population. For example, the SOII does not cover or capture injuries to workers who are self- employed (e.g., independent contractors) or who work on small farms. The 1987 NRC report called spe- cific attention to this problem, and the Bureau of Labor Statistics and other agencies have ongoing efforts to understand the reasons for underreporting and address those that are within its control (BLS, 2017). The underreporting problem, however, is complex and multifactorial (Azaroff et al., 2002). Additionally, there are limitations in the identification and reporting of chronic diseases associated with work. Further, many of the systems that collect information on injuries and illnesses do not collect occupationally-related data. One of the major inputs to OSH surveillance is through the Survey of Occupational Injuries and Ill- nesses (SOII) and the report discusses needed enhancements to the SOII, including those that would better inform surveillance and related public health actions for underserved populations. Injury and illness re- cording, as defined for the SOII, can be improved by better characterization of work-related injuries and illnesses in a manner that enhances usefulness at the worksite as well as at national and state levels (Rec- ommendation A). Developing ways to incorporate information on race and ethnicity as well as employ- ment arrangements will allow for identification of vulnerable worker populations and risks that may be associated with different types of employment arrangements. Substantial progress toward this recommen- dation can be achieved in the near term while some parts will require new methods and resources. The committee supports the BLS plan to implement a Household Survey of Occupational Injuries and Illnesses (HSOII) as it will fill in data gaps for populations of workers who are missing from employ- er-based injury reporting and will provide worker input (Recommendation D). Already being piloted, this survey would fill in important recognized gaps in the SOII coverage. Another largely untapped resource for injury surveillance data is the workers’ compensation system and the report promotes the expanded use of workers’ compensation data for occupational injury and illness surveillance (Recommendation F). Work-related disease information has been almost absent from all efforts at occupational health sur- veillance. This absence was noted in 1987 and remains today. The committee considers this a priority component of data collection and offers several recommendations to attend to this need. These deal with occupational disease monitoring (Recommendation B), the specification of industry and occupation as core variables in all federal health surveys (Recommendation G), the enhanced assessment of self- reported health through the National Center for Health Statistics or an expanded HSOII (one component of Recommendation D), and the development of a comprehensive approach for exposure surveillance (Recommendations D and H). The latter recommendation addresses the unparalleled opportunity to gain information on the distribution of exposure-related factors in a manner modeled on the highly successful experience in the European Union, which has over 25 years of experience in such efforts. The committee acknowledges that full implementation of these five recommendations will require careful planning and a long-term effort. But there are near term steps that move toward the end goals that warrant immediate attention. Expand Biomedical Informatics Use and Capabilities The effectiveness of the overall system of systems will necessarily depend on utilizing the evolving resources and methods of biomedical informatics. Developments occur so rapidly in this area that a lack of experienced, engaged personnel leads to lost opportunities and compromised system effectiveness. The committee considered several aspects of the informatics need but it would be hard to overemphasize how critically important it is for NIOSH to attract adequate informatics personnel and resources (Recommen- dation J), even while acknowledging the difficulties in recruiting and maintaining informatics experts in the public sector. Chapter 7 offers several specific examples of how informatics capacity can be leveraged to enable NIOSH and other OSH agencies both to use advanced computational and analytical tools and to 168 Prepublication Copy

Next Steps for Improving Worker Safety and Health Through a Smarter Occupational Surveillance System monitor advances in information for the most effective OSH surveillance (Recommendations K, L, and M). Achieving the goals of these three recommendations is expected to take some time but it is essential that the initial steps not be delayed. For occupational health surveillance, a forward-looking aspect of data collection and processing concerns how best to remove the barrier to recording and interpreting occupational information in medical records and in population surveys of all types. The report accordingly recommends that NIOSH, with an evolving biomedical informatics capacity, lead efforts to establish data standards and software tools for coding and using occupational data in electronic health records. As these records increasingly become the standard for practice, there is an opportunity to make substantial long-lasting progress to eliminate barri- ers to linking occupation and disease wherever necessary (Recommendation L). The committee also calls for the creation of a cross-agency effort to develop and evaluate state-of-the-art computational and analyt- ical tools for processing free-text data found in occupational safety and health records of all types (Rec- ommendation M). The benefits that accrue from action on these recommendations will prove invaluable in several arenas in addition to surveillance. Strengthen Data Analysis and Information Dissemination for Prevention Successful collection and processing of surveillance data alone does not make a successful surveil- lance system. The system also requires thoughtful analysis, careful interpretation, and then dissemination to all those who can use the results to engage in public health action for prevention. The committee ac- cordingly also examined needs at this stage of surveillance and is optimistic that there are opportunities immediately available, as well as ones that one can realistically imagine, that can support the pursuit of a smarter OSH surveillance system. Attention to analysis and interpretation is essential when calling on partners to provide new or more data, even if that requirement is facilitated through electronic reporting. It is accordingly essential that a program that provides for better reporting, such as the OSHA electronic reporting initiative, needs to be accompanied by a robust plan for the analysis, interpretation, and dissemination of the resulting infor- mation. The committee thus calls on OSHA and its sister agencies and stakeholders to develop and publi- cize plans to maximize the utility of their new electronic reporting initiative by providing means and methods for ongoing analysis and dissemination of these data with special attention to serving individual employer needs, while simultaneously minimizing duplication of reporting by employers (Recommenda- tion E). State and federal workers’ compensation systems, though offering great potential to contribute im- portant insights into the causes of occupational injury and the effectiveness of prevention programs, are constrained by differences in system architecture and coding approaches when compared to other sources of injury data. The report accordingly calls on NIOSH, with assistance from OSHA, to promote the ex- panded use of workers’ compensation data for occupational injury and illness surveillance and to begin to consider the development of surveillance for outcomes or consequences of injury and illness outcomes (Recommendation F). Dissemination of surveillance findings and analyses in forms and substance so these can be used to inform and evaluate prevention is equal in importance to all that has been discussed thus far. The commit- tee has presented the case for making regular reports to the nation that publicize the overall burden of oc- cupational injury and disease in terms of the burdens on health, the economy, and society so these bur- dens can be better characterized (Recommendation I and Q). The committee also recognizes that NIOSH, OSHA, and BLS are practiced in dissemination, and while the committee provides ideas throughout the report on how these efforts could be enhanced to better serve the prevention goal, there are two areas that rose to the level of formal recommendations. The first is engaging with the scientific community by working with the National Library of Medicine to facilitate easy discovery of important connections be- tween work and disease or injury in published research (Recommendation K). Importantly, the committee also recommends the creation of a smoothly operating alert mechanism that receives, enhances, and rapid- ly publicizes to those who need to act the signals of emerging occupational health problems either as new Prepublication Copy 169

A Smarter National Surveillance System for Occupational Safety and Health in the 21st Century associations of work and illness or injury or of old associations found in new settings (Recommendation N). Appropriate and timely attention to surveillance findings, routine or new, is essential for at prevention and thus requires that a smooth and centralized mechanism or office be established for timely ongoing dissemination of information to all relevant actors (Recommendation O). CONCLUDING REMARKS Worker safety and health is of paramount importance to thriving workers and workplaces, and ac- cordingly to society as a whole. Ensuring and improving worker safety and health is a commitment taken seriously by, and diligently acted upon, by numerous federal, state, and local agencies; workers and worker organizations; employers and employer organizations; and many others. More can be done to in- form and improve these efforts through strengthening OSH surveillance in the United States. With the rapid changes in the nature of work in the United States, and with new risks added to those that have al- ways existed, the nation clearly needs a smarter OSH surveillance system of systems for the 21st century. This report provides the evidence and recommendations for a greatly enhanced OSH surveillance system that is envisioned to be smarter, more dynamic, and more highly coordinated. REFERENCES Azaroff, L. S., C. Levenstein, and D. H. Wegman. 2002. Occupational injury and illness surveillance: Conceptual filters explain underreporting. American Journal of Public Health 92(9):1421-1429. BLS (Bureau of Labor Statistics). 2017. Research on the Completeness of the Injury and Illness Counts from the Survey of Occupational Injuries and Illnesses. Available online at https://www.bls.gov/iif/undercount.htm (ac- cessed August 21, 2017). 170 Prepublication Copy

Next: Appendix A Recommendations »
A Smarter National Surveillance System for Occupational Safety and Health in the 21st Century Get This Book
×
Buy Paperback | $54.00
MyNAP members save 10% online.
Login or Register to save!
Download Free PDF

The workplace is where 156 million working adults in the United States spend many waking hours, and it has a profound influence on health and well-being. Although some occupations and work-related activities are more hazardous than others and face higher rates of injuries, illness, disease, and fatalities, workers in all occupations face some form of work-related safety and health concerns. Understanding those risks to prevent injury, illness, or even fatal incidents is an important function of society.

Occupational safety and health (OSH) surveillance provides the data and analyses needed to understand the relationships between work and injuries and illnesses in order to improve worker safety and health and prevent work-related injuries and illnesses. Information about the circumstances in which workers are injured or made ill on the job and how these patterns change over time is essential to develop effective prevention programs and target future research. The nation needs a robust OSH surveillance system to provide this critical information for informing policy development, guiding educational and regulatory activities, developing safer technologies, and enabling research and prevention strategies that serves and protects all workers.

A Smarter National Surveillance System for Occupational Safety and Health in the 21st Century provides a comprehensive assessment of the state of OSH surveillance. This report is intended to be useful to federal and state agencies that have an interest in occupational safety and health, but may also be of interest broadly to employers, labor unions and other worker advocacy organizations, the workers’ compensation insurance industry, as well as state epidemiologists, academic researchers, and the broader public health community. The recommendations address the strengths and weaknesses of the envisioned system relative to the status quo and both short- and long-term actions and strategies needed to bring about a progressive evolution of the current system.

  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. ×

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

    « Back Next »
  6. ×

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

    « Back Next »
  7. ×

    View our suggested citation for this chapter.

    « Back Next »
  8. ×

    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!