[Taxonomy and assessment of psychological investigation methods in psychotropic drug trials (author's transl)].

Psychological tests are bound with specific goals. Four goal aspects are differentiated: status vs. processdiagnostics, normoriented vs. criterionoriented diagnostic, testing vs. inventarization, measurement of true scores vs. decision oriented diagnostic. Every diagnostic procedure is characterized by a specific personality theory and theory of measurement (classical vs. probabilistic test model). The diagnostic procedures traditionally used for evaluating drugs prefer status diagnostic, normoriented diagnostic, testing and measurement of true scores. Similar one-sidedness in personality theory and theory of measurement restrict validity and usefulness of psychological tests. In clinical practice we find a theoretically and empirically unjustified restriction in the selection of measurement devices on ratings and questionnaires. If we suppose multidimensionality of drug induced changes, we must apply a multimethod approach in outcome studies and use beside ratings and questionnaires behavior observations, objective tests, psychophysiological and neurophysiological measures. We propose a descriptive taxonomy of methods for planning multimethod outcome and process studies. From this taxonomy the methods of measurement for effects and side effects of drugs may be derived. The necessity of the multimethod approach is confirmed by empirical research. With this concept, the following neglected research questions become more obvious: concordance and discordance, synchrony and desynchrony of methods of measurement. We conclude with recommendations for clinical practice and research of outcome and process effects in drug therapy.