Zur Testfairness der aussagepsychologischen Begutachtungsmethodik: eine Bayes-statistische Analyse anhand von 2000 Gutachten

In a credibility psychological assessment, the primary objective is to determine whether a particular statement can be attributed to an actual experience. Such assessments are typically commissioned when the person testifying exhibits characteristics that require psychological expertise such as young age, intellectual disabilities or mental disorders. However, little is known about how these characteristics influence the outcome of their assessment. Furthermore, concerns have been raised that the underlying methodology may disadvantage certain groups or may not be fully applicable to them. To examine these concerns, the present study analyzed a dataset of 2005 expert witness reports using Bayesian statistical regression analysis. The results show that neither the demographic personal nor the clinical psychological characteristics of the testifying individuals exhibit a clear association with assessment outcomes. Instead, all eight regression models display imprecise effect estimates, suggesting that other factors must play a more decisive role. A complementary correlational analysis of criticized characteristics and documented reasons for rejecting the assumption of an experienced event also yielded no evidence of systematic disadvantages. Overall, the findings suggest that the current credibility psychological assessment methodology possesses sufficient test fairness with no empirical indications of limited applicability for individuals of young age, with intellectual disabilities or symptoms of a mental disorder.