Quality assurance in credibility assessment

This article analyzes various levels of the quality discussion that are relevant for credibility assessment. On the highest level, the German Federal Supreme Court's (BGH) leading decision on scientific standards for psychological credibility assessment in 1999 has been exceptionally influential. The particular impact of this decision is that it does not just list general demands or name which topics need to be addressed, but lays down specific methodological standards. This has countered a frequent error in the past: namely, that of treating probabilistic indicators as if they were nomological laws. On the concrete level, the instrument known as the critical appraisal of methods (methodenkritische Stellungnahme) has frequently been used to uncover the quality deficits in existing expert's reports. The article points out that although a critical appraisal of methods is also a scientific instrument that has to meet minimum quality standards, these standards have not always been met in practice. Nonetheless, the best outcome of a specification of quality standards is the application in practice of the current state of knowledge in a discipline. Therefore, it has to be stressed that a viable quality discussion depends crucially on the allocation of sufficient research resources to engage in the evaluation and further development of diagnostic strategies for singlecase assessments.