The Research Data Centre of the Robert Koch Institute (FDZ RKI) publishes the data of population-representative health surveys in the form of public use files (PUFs).The main purpose of health surveys is to generate a maximum amount of information on the state of health and health-related behaviour of Germany's resident population while ensuring an optimum use of funds. The methodology - i.e. the sample design, the principles on operationalization and measurement, and data-collection techniques - is largely modelled on the tried-and-tested methods of empirical social research. Health interview surveys (HIS) use established survey techniques such as filling out questionnaires, computer-assisted telephone interviews (CATI), computer-assisted personal interviews (CAPI), and online polling via the internet or email. The main difference compared to purely sociological surveys lies in the additional biomedical examinations, tests and medical-biochemical measurements, which generate significant added value in addition to the results of the surveys; this part is referred to internationally as the health examination survey (HES).