9c. Making Decisions with Incomplete Evidence   

In an ideal world, all population health programs and policies would be based on high-quality, robust scientific evidence. But the reality is that public health decision makers often have to take action in the absence of conclusive information about the effectiveness of public health interventions.

For example, the need to control pressing public health problems, such as rapid increases in childhood obesity, cannot wait for conclusive evidence on the optimal mix of effective interventions. All available information must be weighed: assessment data on the magnitude of the problem, epidemiologic data on determinants, stakeholder and public opinion on the nature of the problem and acceptable solutions, existing practices and traditions, evaluations from promising programs and policies, legal considerations such as privacy laws, budgetary constraints, and political resolve. 

If all public health decisions required convincing scientific evidence, new innovative programs and policies could never emerge. If we waited for all the evidence to emerge before implementing policies and programs, then our evidence base would be restricted to a very narrow range of studies conducted under tightly controlled conditions that may lack broad generalizability. 

If, for example, we had waited for a comprehensive list of evidence-based tobacco-control interventions before taking action to curb smoking we would only now be beginning to address tobacco smoking, resulting in countless millions of additional lives lost around the globe. Even now, we know that it is best to help smokers quit at as young an age as possible, but we lack complete information about the types of cessation programs that are most effective with adolescent smokers. Does this mean we should wait to take action? Of course not.

Girl smoking in foreground, with another girl with a look of disgust on her face in the background