National Academies Press: OpenBook

Integrating Systems and Sectors Toward Obesity Solutions: Proceedings of a Workshop (2021)

Chapter: 5 Examples from the Field: Applying Systems Thinking to Population Health Issues

« Previous: 4 Impacting Complex Systems That Can Influence Obesity
Suggested Citation:"5 Examples from the Field: Applying Systems Thinking to Population Health Issues." National Academies of Sciences, Engineering, and Medicine. 2021. Integrating Systems and Sectors Toward Obesity Solutions: Proceedings of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/25766.
×

5

Examples from the Field: Applying Systems Thinking to Population Health Issues

Suggested Citation:"5 Examples from the Field: Applying Systems Thinking to Population Health Issues." National Academies of Sciences, Engineering, and Medicine. 2021. Integrating Systems and Sectors Toward Obesity Solutions: Proceedings of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/25766.
×

The workshop’s final session featured three speakers who shared field examples of how research is exploring the application of systems thinking to address obesity and population health. Sara Bleich, professor of public health policy at the Harvard T.H. Chan School of Public Health and the Carol K. Pforzheimer Professor in the Radcliffe Institute for Advanced Study at Harvard University, moderated the session.

PHYSICAL ACTIVITY

John Jakicic, director of the Healthy Lifestyle Institute and chair of the Department of Health and Physical Activity at the University of Pittsburgh, discussed examples of integrating systems and sectors to promote physical activity. He described his university’s work as a “living laboratory” that aims to translate research center–based initiatives into broader, institution- and community-based initiatives. He expounded on lessons learned from the process of translating initiatives into these broader systems contexts.

The research center–based initiatives, Jakicic began, revolve around physical activity for the prevention and treatment of obesity. They involve classical measurements collected in controlled laboratory settings, randomization, and participant eligibility criteria, he said, and they provide signals of things that could work in the field even though they do not fully represent real-world settings.

Jakicic explained that laboratory work in research settings helps form a foundation for the content that is applied in institution-based initiatives. He shared examples of his team’s translation of learnings from the research environment into interventions within the broader University of Pittsburgh setting, which employs 15,000 adults. The team believed that building a community of physical activity in the university environment was a precursor to expanding that community beyond the university setting, he noted, and then throughout the city of Pittsburgh more broadly.

Jakicic reported that the team began by surveying members of the university community about supports for physical activity, and received feedback centered on a desire for more exercise facilities and equipment. He pointed out, however, that targeting exercise is markedly different from promoting physical activity. Furthermore, he continued, the team determined that only a small percentage of adults at the university (estimated by Jakicic as approximately 500 out of 15,000 people) are regular fitness center users; therefore, an investment in additional facilities and equipment would likely not reach the vast majority of the target audience. Jakicic also described feedback from individuals not engaged in exercise who indicated that they avoided fitness facilities for such reasons as intimidation (i.e., the perception that their relative lack of knowledge about how to engage in structured exercise would make them feel out of place), dislike of their

Suggested Citation:"5 Examples from the Field: Applying Systems Thinking to Population Health Issues." National Academies of Sciences, Engineering, and Medicine. 2021. Integrating Systems and Sectors Toward Obesity Solutions: Proceedings of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/25766.
×

appearance when they exercised, and dislike of exercise in general. However, he said, these individuals were willing to engage in other forms of physical activity.

The survey findings, Jakicic continued, led the team to think more broadly about the kinds of initiatives that would draw the rest of the university population into a more physically active lifestyle. He described his team’s discovery that a key element of building a community of physical activity is to make people feel as though they are part of something together with others who are just like them. This discovery, he said, led to the birth of the Be Fit Pitt initiative, which attracted people who were not regular exercisers but who wished to move more as they viewed activity from the perspective of a healthier lifestyle. The team drew on laboratory research–based findings indicating that individuals with low activity levels are more likely to sustain physical activity if new activity options are introduced every 8 to 12 weeks, which prompted the creation of regular programming opportunities for engagement in physical activity. Jakicic mentioned several themed activities that leveraged holidays, encouraged friendly competition, and engaged people in fun ways to be active. The initiative started to catch on, he recounted, and grew as the university community was creatively activated on an ongoing basis and activities were modified over time.

Gradually, Jakicic continued, the team introduced remote opportunities for people to engage in physical activity, such as livestreamed or recorded video activities. The benefit of this strategy, he explained, is that it satisfies participants’ desire to engage in physical activity without feeling the intimidation of being visible. He highlighted PittWire Live as an example of an online platform that has received positive feedback, explaining that its livestreamed physical activity sessions are able to reach communities beyond the university campus.

Jakicic went on to describe how his team approached expanding the Be Fit Pitt initiative into the broader community. They quickly learned that the traditional exercise facilities in communities were often small, dingy, and generally unappealing, he reported, which propelled them to consider more engaging ways to activate people. He described how they discovered that a key strategy was to make activity accessible for people at different levels of fitness and self-efficacy, such as by providing relatable models and a variety of activity options to suit people’s varying fitness levels. Jakicic acknowledged, however, that livestreamed programming does not work for communities without adequate computer equipment and reliable Internet access, and he urged initiatives to consider how to reach the largest possible number of people.

Finally, Jakicic highlighted examples of how the University of Pittsburgh partners with surrounding communities to understand what would work to encourage and facilitate physical activity in their unique contexts. He

Suggested Citation:"5 Examples from the Field: Applying Systems Thinking to Population Health Issues." National Academies of Sciences, Engineering, and Medicine. 2021. Integrating Systems and Sectors Toward Obesity Solutions: Proceedings of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/25766.
×

described community engagement centers, where university representatives host community discussions not for the purpose of formal research, but to understand community needs and assets.

DESIGN OF MULTILEVEL INTERVENTIONS FOR OBESITY

Bonnie Spring, professor of preventive medicine, psychology, psychiatry, and public health at Northwestern University and director of its Center for Behavior and Health within the Institute for Public Health and Medicine, discussed the design of multilevel interventions to treat obesity. She began by describing a basic premise of the socioecological intervention framework: interventions that target determinants at multiple levels of that framework produce larger and longer-lasting effects relative to interventions that target only one level (Weiner et al., 2012). With regard to clinical treatment of obesity, Spring pointed to the Diabetes Prevention Program (DPP), which the U.S. Preventive Services Task Force considers the “gold standard.” She described the DPP as an intensive, multicomponent behavioral treatment, which grew out of a successful weight loss and diabetes prevention intervention that was tested in multiple sites in 2002. Initially, the DPP treatment package involved 24 one-on-one, in-person treatment sessions led by health professional counselors, Spring explained, but now it is common to have group sessions led by trained lay counselors at a much lower cost.

Spring described how her team optimized the DPP by studying which additional dimensions of the socioecological model beyond the individual level produced enhanced weight loss when targeted by the intervention (see Figure 5-1). She explained that all participants received a core intervention that was remote and targeted the individual level by promoting app-based self-monitoring of daily weight, dietary intake, and physical activity, as well as by providing coaching calls. Half of the participants received 12 calls from a coach who offered counseling based on the digitally transmitted self-monitoring data, while the remainder of the participants received more intensive coaching consisting of 24 calls. All participants joined the trial with a support buddy. Spring explained that the intervention targeted the interpersonal level for half of the sample by training the support buddies in how to provide support; buddies for the remainder of the sample received no such training. The intervention targeted the organizational level, Spring said, by sending weight loss progress reports to the primary care providers for half of the sample but not the remainder. She acknowledged that the environmental and policy level posed more of a challenge, but the intervention was able to offer 1 week of portion-controlled meal replacements and then recommendations for meal replacements in subsequent weeks. Ultimately, Spring said, the intervention aimed to discover which treatment components would contribute most to 6-month weight loss and at what cost.

Suggested Citation:"5 Examples from the Field: Applying Systems Thinking to Population Health Issues." National Academies of Sciences, Engineering, and Medicine. 2021. Integrating Systems and Sectors Toward Obesity Solutions: Proceedings of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/25766.
×
Image
FIGURE 5-1 Ecological model for obesity intervention.
NOTE: PCP Report = primary care provider weight loss report; Recs = recommendations; Tx = treatment.
SOURCE: Presented by Bonnie Spring, June 30, 2020. Reprinted with permission.

Turning to the intervention results, Spring noted that 562 people were randomized, and the 6-month retention rate was 84.3 percent. The component that significantly increased weight loss was buddy support, she reported, an effect that was enhanced when the weight loss progress report was sent to a primary care provider. Perhaps the reason why 24 coaching calls produced no more weight loss than 12 calls, she hypothesized, was because participants’ self-regulation training needs were met by the lower level of coaching. Thus, additional weight loss was not seen unless the intervention also targeted the interpersonal and organizational levels of the ecological model. Spring reviewed a table populated with the intervention data to demonstrate how to build a treatment package that maximizes 6-month weight loss for less than $500: a remotely delivered weight loss intervention comprising an app, 12 digitally connected coaching sessions, buddy training, and primary care progress reports produced 7 percent weight loss for 52 percent of the sample, a result comparable to that of the original DPP in-person intervention at less burden and cost ($427). Particularly when limited resources call for best-value solutions to extend treatment to the greatest number of people, Spring added, a $324 trimmed-down version

Suggested Citation:"5 Examples from the Field: Applying Systems Thinking to Population Health Issues." National Academies of Sciences, Engineering, and Medicine. 2021. Integrating Systems and Sectors Toward Obesity Solutions: Proceedings of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/25766.
×

of the intervention involving only the app plus 12 coaching calls produced 5 percent weight loss for 53 percent of the sample (Spring et al., 2020).

Spring went on to discuss how the DPP has moved from hospital- and health care–based delivery systems into community settings. The program has been scaled successfully in YMCAs, she reported, yet engages relatively few of its intended recipients. She asserted that this is the case because place-based programs present such barriers as transportation and child care, which disenfranchises the target audience. Spring called for linkages that can promote both scale and reach by spanning the dimensions of care delivery, community services, and family and individual engagement and empowerment.

In summary, Spring maintained that multilevel interventions are promising and encouraged understanding multilevel systems synergies and constraints on implementing obesity interventions. Finally, she appealed for continual optimization for effectiveness and efficiency within the context of change.

LESSONS FROM COMMUNITY-BASED OBESITY PREVENTION IN AUSTRALIA

Steve Allender, professor of population health and founding director of the Global Obesity Center (a World Health Organization Collaborating Center for Obesity Prevention) at Deakin University, shared lessons from community-based obesity prevention trials in Victoria, Australia. He described a relatively new and commonly used trial design, a stepped wedge cluster randomized trial in which some intervention communities are active at earlier and others at later points in the study. The trial design builds on a 20-year history of community-based interventions, which Allender said imparted several lessons: childhood obesity is preventable; community-led interventions targeting various stages of childhood can be effective; multilevel strategies are important; local ownership and leadership are critical; implementation is often time-consuming and challenging; and if these lessons are not applied, sustainability is likely to be limited, especially in a climate of fluctuation in political support. According to Allender, these lessons helped researchers recognize the importance of giving communities tools and techniques to address the complexity of conditions because their contexts are vastly different.

Allender next provided an overview of the intervention in Victoria, which follows a nonlinear process. An early step is to engage a catalyst in each community, whom he described as a person who is well-connected and motivated to do the work. Researchers work with the catalyst to engage local leadership, he explained, using methods from systems science approaches, particularly system dynamics and group model building, to develop a shared understanding of the complexity of the causes and outcomes of overweight

Suggested Citation:"5 Examples from the Field: Applying Systems Thinking to Population Health Issues." National Academies of Sciences, Engineering, and Medicine. 2021. Integrating Systems and Sectors Toward Obesity Solutions: Proceedings of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/25766.
×

and obesity in each community. According to Allender, the researchers’ role is to provide the evidence base and help the community understand how it might inform community action, and then to support the community’s momentum for change by building capacity; providing tools and resources; and providing monitoring, evaluation, and feedback.

Allender displayed a causal loop diagram constructed by community stakeholders as part of a whole-of-systems approach to addressing childhood overweight and obesity in Campbelltown, Australia. The diagram is color-coded, he explained, to distinguish subsystems of interest such as physical activity, nutrition, education, and social determinants of health. A benefit of the causal loop diagram, he observed, is that community stakeholders can begin to see where they best fit into a response to obesity. Another is that it can be used to track actions corresponding to the issues illustrated by the diagram, he added, recounting that 8 actions had been taken 3 months into the intervention and 63 actions by the 2-year mark. The actions operate at multiple levels and in different parts of the community, he pointed out, but most important, they are backed by community interest and capacity.

Next, Allender highlighted STICKE,1 software invented by his group to help communities facilitate the process of creating causal loop diagrams and tracking actors and actions. He showed a portion of the Campbelltown causal loop diagram that included actors, actions, and the connections among them. Some of the connections represent new relationships among stakeholders, he noted, who have joined together with a new focus on specific actions to improve child health. Allender observed that tracking of actions has revealed the scope of topics that communities are addressing. He referenced a community in Western Victoria that was part of the Whole of Systems Trial of Prevention Strategies for childhood obesity (WHO STOPS childhood obesity) study, with 480 actions in some level of implementation. It was encouraging to see that many of the actions were related to healthy eating, he remarked, which aligned with evidence suggesting the need to emphasize food choices.

Sharing interim results, Allender reported that on average these community-based trials result in a 4 percent reduction in the prevalence of overweight and obesity over the first 2 years, but he noted that further work is needed to understand the longer-term outcomes. He added that significant improvement is seen in health-related quality of life among children in the intervention communities, as are positive changes in obesity-related behaviors over the long term. By combining a range of methods with systems science approaches, Allender said, researchers can better understand and respond to the complexity of childhood obesity.

___________________

1 See https://sticke.deakin.edu.au (accessed October 5, 2020).

Suggested Citation:"5 Examples from the Field: Applying Systems Thinking to Population Health Issues." National Academies of Sciences, Engineering, and Medicine. 2021. Integrating Systems and Sectors Toward Obesity Solutions: Proceedings of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/25766.
×

AUDIENCE DISCUSSION

Bleich moderated a discussion with the three speakers following their remarks. The discussion covered community perceptions of systems science approaches, technology to enable remote delivery of interventions, reconciling individual perspectives with systems science approaches, engaging the private sector, and lessons from community engagement.

Community Perceptions of Systems Science Approaches

Bleich asked Allender to describe how communities in Australia perceive a systems science approach to obesity prevention compared with a more traditional approach. Allender replied that a systems science approach is more logical from a community’s point of view, and described how his team presents this approach as a way of thinking that might be helpful and then allows communities to opt in to proceed. Gaining initial buy-in from the community instills a level of confidence among community leaders, he added, who might risk a loss of social capital if they agreed to an approach disliked by community members. Group model building occurs at the beginning of the intervention, he continued, which excites the community to keep moving forward as it becomes possible to visualize the problem with its complexity and feedback loops. According to Allender, this process helps community members find ways to work together that are evidence-informed and respect the complexity of the problem and its context, a benefit that traditional methods cannot provide.

Technology to Enable Remote Delivery of Interventions

Bleich asked Spring to suggest solutions for the challenges of recruitment and retention of participants for YMCA-based DPPs. Spring replied that potential participants are dispersed across many different geographic areas, and may have limited time and resources to attend in-person treatment sessions. She observed that the coronavirus disease 2019 (COVID-19) pandemic has illuminated the promise of delivering interventions remotely, and mentioned studies indicating positive results from delivering the DPP with online and asynchronous Internet communication via federally qualified health centers. She pointed out that people often perceive technology as a limiting factor for underresourced communities, but that what she termed a “reverse digital divide” exists for access to mobile tools. She noted that Black and Hispanic communities have used mobile health tools extensively, and suggested that these tools may be promising for outreach to older adults if they are taught how to use them and can access technological support as needed. Jakicic concurred, referencing a survey of older adults

Suggested Citation:"5 Examples from the Field: Applying Systems Thinking to Population Health Issues." National Academies of Sciences, Engineering, and Medicine. 2021. Integrating Systems and Sectors Toward Obesity Solutions: Proceedings of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/25766.
×

indicating that a majority want to have remote options for receiving help. He hypothesized that this finding may reflect a desire for convenience and regular touchpoints.

Reconciling Individual Perspectives with Systems Science Approaches

Recalling the finding by Jakicic’s team of varying individual perspectives on physical activity, Bleich asked him how that diversity can be reconciled with the application of systems science approaches. Jakicic reiterated that viewing physical activity as exercise is a barrier for some people, and that certain forms of physical activity requiring greater financial investment or higher fitness levels are less accessible. He called for a broad scope of activity options to reach the greatest number of people.

Engaging the Private Sector

Bleich next asked the speakers about ideas for engaging the private sector in obesity prevention. Allender suggested inviting business owners and leaders to contribute as members of the community, as well as including businesses in trial design. As an example of the latter, he referenced initiatives in which supermarket efforts to modify food presentation and marketing have resulted in changes in purchasing patterns. He shared his experience with a ready and willing business community, urging others not to overlook this powerful resource. Spring mentioned the existence of obesity interventions in large worksites and highlighted the American Heart Association’s CEO Roundtable, a leadership collaborative dedicated to implementing evidence-based approaches to workplace health that focus on engaging employees and building a corporate culture of health. She also pointed to a tremendous interest in commercializing health interventions, which she identified as an opportunity for beneficial dialogue with potential collaborators.

Lessons from Community Engagement

The final question solicited the three speakers’ thoughts on how engagement with communities has influenced their research priorities and study designs. Jakicic described a needs analysis that was conducted in a community before an intervention was developed, explaining that it helped researchers identify respected individuals perceived by community members as core leaders. The experience helped the researchers understand how best to engage the community, he recalled, and identified key influencers with whom researchers should partner. Spring stressed the importance of cultivating humility and trust so it is clear that researchers understand the

Suggested Citation:"5 Examples from the Field: Applying Systems Thinking to Population Health Issues." National Academies of Sciences, Engineering, and Medicine. 2021. Integrating Systems and Sectors Toward Obesity Solutions: Proceedings of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/25766.
×

community’s needs. Allender called for researchers to recognize that their role is to provide tools and opportunities for communities to solve problems in the way that makes sense for them.

CLOSING REMARKS FOR PART II

Christina Economos, co-founder and director of ChildObesity180 and professor and New Balance chair in childhood nutrition in the Friedman School of Nutrition Science at Tufts University, reflected on themes that had emerged from the workshop presentations and discussions. She highlighted examples of structural and social drivers with the potential to shape public health and offer opportunities for systems change as they relate to obesity solutions, including context, inequities, structural racism, disparities, bias, power dynamics, relationships, mindset, trust, humility, engagement, multilevel interventions, and technology. Nicolaas Pronk, president of HealthPartners Institute, chief science officer at HealthPartners, and chair of the Roundtable on Obesity Solutions, shared his takeaways from the workshop, emphasizing the importance of leadership, humility, community engagement, stakeholder involvement, building trust, and appreciating complexity as crucial to progress and impact. Pronk ended Part II of the workshop with a preview of the roundtable’s September 2020 workshop. He indicated that although both qualitative (e.g., mapping) and quantitative (e.g., modeling) systems science approaches are important, the follow-on workshop will focus on modeling of various approaches that could guide future obesity research and action and on support structures for those approaches.

Suggested Citation:"5 Examples from the Field: Applying Systems Thinking to Population Health Issues." National Academies of Sciences, Engineering, and Medicine. 2021. Integrating Systems and Sectors Toward Obesity Solutions: Proceedings of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/25766.
×
Page 69
Suggested Citation:"5 Examples from the Field: Applying Systems Thinking to Population Health Issues." National Academies of Sciences, Engineering, and Medicine. 2021. Integrating Systems and Sectors Toward Obesity Solutions: Proceedings of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/25766.
×
Page 70
Suggested Citation:"5 Examples from the Field: Applying Systems Thinking to Population Health Issues." National Academies of Sciences, Engineering, and Medicine. 2021. Integrating Systems and Sectors Toward Obesity Solutions: Proceedings of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/25766.
×
Page 71
Suggested Citation:"5 Examples from the Field: Applying Systems Thinking to Population Health Issues." National Academies of Sciences, Engineering, and Medicine. 2021. Integrating Systems and Sectors Toward Obesity Solutions: Proceedings of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/25766.
×
Page 72
Suggested Citation:"5 Examples from the Field: Applying Systems Thinking to Population Health Issues." National Academies of Sciences, Engineering, and Medicine. 2021. Integrating Systems and Sectors Toward Obesity Solutions: Proceedings of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/25766.
×
Page 73
Suggested Citation:"5 Examples from the Field: Applying Systems Thinking to Population Health Issues." National Academies of Sciences, Engineering, and Medicine. 2021. Integrating Systems and Sectors Toward Obesity Solutions: Proceedings of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/25766.
×
Page 74
Suggested Citation:"5 Examples from the Field: Applying Systems Thinking to Population Health Issues." National Academies of Sciences, Engineering, and Medicine. 2021. Integrating Systems and Sectors Toward Obesity Solutions: Proceedings of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/25766.
×
Page 75
Suggested Citation:"5 Examples from the Field: Applying Systems Thinking to Population Health Issues." National Academies of Sciences, Engineering, and Medicine. 2021. Integrating Systems and Sectors Toward Obesity Solutions: Proceedings of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/25766.
×
Page 76
Suggested Citation:"5 Examples from the Field: Applying Systems Thinking to Population Health Issues." National Academies of Sciences, Engineering, and Medicine. 2021. Integrating Systems and Sectors Toward Obesity Solutions: Proceedings of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/25766.
×
Page 77
Suggested Citation:"5 Examples from the Field: Applying Systems Thinking to Population Health Issues." National Academies of Sciences, Engineering, and Medicine. 2021. Integrating Systems and Sectors Toward Obesity Solutions: Proceedings of a Workshop. Washington, DC: The National Academies Press. doi: 10.17226/25766.
×
Page 78
Next: References »
Integrating Systems and Sectors Toward Obesity Solutions: Proceedings of a Workshop Get This Book
×
Buy Paperback | $60.00 Buy Ebook | $48.99
MyNAP members save 10% online.
Login or Register to save!
Download Free PDF

A virtual workshop titled Integrating Systems and Sectors Toward Obesity Solutions, held April 6, 2020 (Part I), and June 30, 2020 (Part II), was convened by the Roundtable on Obesity Solutions, Health and Medicine Division, National Academies of Sciences, Engineering, and Medicine. The workshop introduced the concept of complex systems and the field of systems science, and explored systems science approaches to obesity solutions. Speakers provided an overview of systems science theories, approaches, and applications, highlighting examples from within and outside the obesity field. Presentations and discussions examined complex systems in society that have the potential to shape public health and well-being, and considered opportunities for systems change as they relate to obesity solutions. Specifically, the workshop explored factors that can influence obesity - such as (in)equity, relationships, connections, networks, capacity, power dynamics, social determinants, and political will - and how these factors can impact communications and cross-sector collaboration to address obesity. This publication summarizes the presentations and discussion of the workshop.

  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!