The first task is to define with precision the program(s) or intervention(s) to be evaluated. For each intervention or program included in the study, identify the following elements:
the nature of the intervention(s) (e.g., a vaccination program for smallpox),
the target population(s) (e.g., general population, health-care workers, and investigation team),
the delivery site(s) (e.g., public health department clinics),
the personnel delivering the service (e.g., public health nurses [PHNs]),
the technology to be used (e.g., circulating smallpox vaccine), and
the timing of the intervention (e.g., August 2003).
Precision is critical because programs that appear to be similar might have substantially different costs and outcomes.