As soon as the first contact with a target person was made, interviewers completed an Observation Protocol. On the one hand, this allowed the form and content of early contacts with both non-participants and study participants at various levels of participation to be recorded in a standardized manner. On the other hand, the interviewer observations and assessments documented would enable an appraisal of sample selectivity if the active participation of the particular target person was not possible.
It did not initially play any role whether the contact occurred over telephone or face-to-face, the Observation Protocol was always completed immediately after the first contact. The information recorded was not gathered from the participant, but was based solely on the observations of the interviewer. Extra details were only included in cases where third parties, of their own accord, gave plausible-sounding information relating to the Observation Protocol items. In order for the Observation Protocol to be fully completed, the participant-interviewer contact had to last at least 15 minutes. This minimum duration was necessitated by the question complex for the psychiatric items.
When the first contact occurred over telephone, the possibilities of gathering data for the Observation Protocol were, of course, much reduced. If face-to-face contact occurred at a later date, the Observation Protocol based on the telephone contact was destroyed and a new one completed, direct personal contact in the participant's home allowing substantially more observation data to be gathered.
Information was gathered on the housing conditions and residential environment, the "setting" of the contact health impairment and indications of needs for health and care as well as data on specific behavior and speech characteristics which could indicate mental illness.