Recall that epidemiology is the study of the occurrence of disease in human populations and offers a methodology for determining the objective importance of health problems in a target population. By showing the magnitude and distribution of health problems in the population, descriptive epidemiological data suggest the relative importance of the health problems in terms of morbidity, disability, or mortality. Such data also suggests how the importance of health problems varies among subgroups of the population that differ in age, race, gender, lifestyle, housing, or exposure to specific behavioral or environmental risk factors. The epidemiological assessment thus identifies those health problems and risk factors, that deserve priority among the many problems a program might address. Prevalence measures the total number of existing disease cases at a particular point in time, reflecting both incidence and the duration of the disease and complicated by prognosis.
Incidence is the number of new cases of a disease within a period of time.
Since these are the risk factors that the intervention is tailored to affect, they must be very specifically identified and carefully ranked. Both behavioral and environmental factors are linked to health and quality of life. Educational and organizational diagnosis examines those behavioral and environmental conditions linked to health status or quality of life concerns to determine what causes them. The educational and organizational diagnosis identifies factors that must be changed to initiate and sustain the process of behavioral and environmental change. These factors will become the immediate targets or objectives of the program.