[What studies are useful within the scope of quality assurance?]

The necessity for studies in quality assurance is based on the demand for evaluation of quality assurance measures. Whereas investigation of effects of quality assurance measures under controlled conditions is the goal of quality research, quality assurance deals with the improvement and assurance of quality under routine conditions. In quality research a far reaching control of bias and confounding variables should be aimed at. This is only possible with controlled studies, preferably with the randomised study. With methodological demanding randomised studies the effectiveness of specific quality instruments (e.g. guidelines) could be demonstrated. In the evaluation of quality assurance comparison is also the major principle. This can be done in a controlled non-randomised study, in an empiricle comparison between institutions or in a comparison with a given quality standard. It is hoped, that also in Germany methodological adequate studies will play a major role in quality research and quality assurance in the future.