A program for studying a group or population, in order to assess its health status, the conditions influencing or influenced by its health, and the health services and medical care available to and used by it.
An investigation of an area or population in order to obtain information about some aspect of the health of its population (its health problems, its health resources, or anything else pertaining to health). Such a survey typically employs sampling, and may obtain information from direct observations, questionnaires, published data, or other sources.