intervention, for example, there will be a multiplicity of points of intervention, from individuals to families, social groups, organizations, whole communities, regions, or states, each calling for different sources or types of evidence. Complexity will further confound the translation of evidence with respect to the projected time frame, even across the lifespan, to account for variations in interventions that make them age-appropriate and account for such relevant background variables as media coverage of the issue, social discourse, and changing social norms.


This section examines the need to take advantage of natural experiments and emerging and ongoing interventions as sources of practice-based evidence to compensate for the fundamental limitations of even the best available evidence.

Natural Experiments as Sources of Practice-Based Evidence

Rather than waiting for the funding, vetting, implementation, and publication of RCTs (and other forms of research) to answer practical and locally specific questions, one alternative is to treat the myriad programs and policies being implemented across the country as natural experiments (Ramanathan et al., 2008). Applying more systematic evaluation to interventions as they emerge, even with limited experimental control over their implementation, will yield more immediate and practice-based evidence for what is possible, acceptable, and effective in real-world settings and populations. What makes such evaluation of these natural experiments even more valuable is that it produces data from settings that decision makers in other jurisdictions can view as more like their own than the settings of the typical published trials. Seeing how other state and local jurisdictions are performing in a given sphere of public concern also may activate competitive instincts that spur state and local decision makers to take action.

The Centers for Disease Control and Prevention’s (CDC’s) Office on Smoking and Health used this strategy of making comparisons across jurisdictions when California and Massachusetts raised cigarette taxes and launched tax-based, comprehensive statewide tobacco control programs (see Chapter 4). Noting the accelerated rates of reduced tobacco consumption in those states compared with the other 48 states, CDC collaborated with the two states to evaluate these natural experiments and analyze their components (e.g., mass media, school programs) and the associated costs. CDC then offered the per capita costs of each component as a recommended basis for budgeting for other states wishing to emulate these successful programs (CDC, 1999). Many of the states used these budgetary allocations, at least temporarily before the tobacco settlement funds from the tobacco industry were diverted to general revenue or other purposes.

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