The checklist could test whether the activity is preventive, (e.g. primary or secondary reason for service is to prevent the need for acute care; treatment for sexually transmitted disease is to prevent transmission of disease); whether it benefits a population (this does not preclude services to individuals -the benefit could be to an individual and a population, e.g. immunisation); whether a public health response is required in addition to (any) individual treatment response required (e.g. assess area for contaminant after individual exposure, check cooling towers in response to case of Legionnaires disease, trace contacts of person diagnosed with infectious disease); whether it is an organised response, for instance, in response to a disaster, over time (e.g. immunisation register), or in scale (e.g. screening across the nation, quality assurance through pathology reference laboratories).