of locating, evaluating, and assembling evidence; and, most important, the existence of relevant evidence. Use of the L.E.A.D. framework to broaden what is considered useful, high-quality evidence and to gradually increase the availability of such evidence will help in attaining this standard. Together with the importance of taking a systems approach and making the best possible use of diverse types of evidence that are relevant to the user’s perspective and the question being asked, a major emphasis of this report is the urgent need to generate more evidence to inform efforts to address obesity prevention and other complex public health problems. Much of what is called for in the framework will meet the expectations and needs of decision makers when sufficient evidence exists, although clearly such is not yet the case (see Chapter 3). On the other hand, failure to find relevant evidence may either (erroneously) reinforce the perception that effective interventions cannot be identified, or increase skepticism or resistance on the part of decision makers—who must proceed in the interim—with respect to the utility of incorporating evidence into their decision-making process. As described in Chapter 7, when decision makers face choices that must be made and actions that must be taken in the relative absence of evidence, or at least on the basis of inconclusive, inconsistent, or incomplete evidence, the L.E.A.D. framework calls for critical evaluation and systematic building on experience in a continuous translation, action, monitoring, surveillance, and feedback loop (i.e., matching, mapping, pooling, and patching; see Appendix E for more detail).
The purpose of this chapter is to motivate researchers and others whose primary role is to generate (i.e., support, fund, publish) evidence to adopt the L.E.A.D. framework as a guide to identifying and generating the types of evidence that are needed to support decision making on obesity prevention and other complex public health problems (see Figure 8-1). The focus is on evidence related to “What” and “How” questions, that is, evidence demonstrating the types of interventions that are effective in various contexts; what their impacts are; and which are relatively more or less effective, whether they are associated with unexpected benefits or problems, and what practical issues are involved in their implementation. As noted in Chapter 3 and defined in Chapter 5, these concerns point to areas in which a lack of evidence is most likely to be problematic. This chapter also anticipates a cycle that begins with planning from incomplete evidence, blended with theory, expert opinion, experience, and local wisdom (see Chapter 7), and ends with evaluating the consequences of interventions. Such a cycle, in turn, may produce the most credible evidence for other jurisdictions seeking practical models to emulate.
The chapter begins by briefly reviewing existing evidence needs and outlining the need for new directions in evidence generation and transdisciplinary exchange. It then addresses the limitations in the way evidence is reported in scientific journals and the need to take advantage of natural experiments and emerging and ongoing interventions as sources of practice-based evidence to fill the gaps in the best available evidence. The chapter concludes with a discussion of alternatives to randomized