Evidence-based public health has become an often-used phrase by both practi-tioners and policymakers. However, its meaning and proper place in the devel-opment, conduct, and evaluation of public health programs and policies are
often misunderstood. When we hear the word evidence, most of us conjure up the mental picture of a courtroom, with opposing lawyers presenting their evidence, or of law enforcement personnel sifting through a crime scene for evidence to be used in judicial proceedings. Evidence, so central to our notion of justice, is equally central to public health. It should inform all of our judgments about what policies, programs, and system changes to implement, in what populations, and what will be the expected result. For example, “Is the goal to improve the health and well-being of the target population equally, or to also reduce health inequities, because the distribution of ill-health and injuries is so skewed in virtually all geopoliti-
cal units?” In public health, there are four principal user groups for evidence. Public health practitioners with executive and managerial responsibilities and their many public and private partners want to know the evidence for alternative strategies, whether they are policies, programs, or other activities. Too infre-quently do busy practitioners find the time to ask the fundamental question,“What are the most important things I can do to improve the public’s health?”In pursuit of answers, population-based data are the first prerequisite, cover-
ing health status, health risks, and health problems for the overall population

and sociodemographic subsegments. Also important are the population’s atti-
tudes and beliefs about various major health problems.

The second prerequisite is data on potential interventions. What is the
range of alternatives? What do we know about each? What is their individual

and conjoint effectiveness in improving health in the populations we are serv-
ing? And what is the relative health impact per dollar invested for single or

combined interventions? This marriage of information can lead to a rational
prioritization of opportunities, constrained only by resources and feasibility.