According to the established definition of Pfaff, health services research analyses patients' path through the institutions of the health care system. The focus is on development, evaluation and implementation of innovative measures of health care. By increasing its quality health services research strives for an improvement of efficacy and efficiency of the health care system. In order to allow for an appropriate evaluation it is essential to differentiate between structure, process and outcome quality referring to (1) the health care system in its entirety, (2) specific health care units as well as (3) processes of communication in different settings. Health services research comprises a large array of scientific disciplines like public health, medicine, social sciences and social care. For the purpose of managing its tasks adequately a special combination of instruments and methodological procedures is needed. Thus, diverse techniques of evaluation research as well as special requirements for study designs and assessment procedures are of vital importance. The example of the German disease management programmes illustrates the methodical requirements for a scientific evaluation.
