[Diagnostic judgement and evaluation]

The present article provides an overview of principles and standards for diagnostic decisions and evaluation. Assessment aims to answer concrete questions. Clinical and statistical judgements represent two strategies for the integration of diagnostic information. It is illustrated that the hit-rate is closely linked to validity, base-rate, and selection-rate. Depending on the psychological question it might be necessary to either detect many "appropriate" or reject many "inappropriate" persons (sensitivity-specificity). In the case of multiple criteria three strategies are available, for which adequate practical applications are proposed. As far as the assessment process is concerned, recommendations are available for hypothesis-guided data collection and integration. As a special assessment problem simulation/aggravation is discussed. A listing of quality aspects shows how to identify good evaluations. Finally, procedures to maintain a high quality are recommended.