Practicable and valid approach to evaluate the efficacy of nootropic drugs by means of rating scales.

Starting with the disputable practice of evaluating the efficacy of nootropic drugs the author has developed a strictly experimental examination approach emphasising the internal validity of experiments. The physician's assessment of the global therapeutic effect is suggested as a variable examination factor which should be treated as an independent variable and a valid instrument for judging the effect when arriving at a statistical conclusion. Differentiated rating scales and measurements are suggested as a basis for this judgment. Proven effects are described in a more differentiated manner by means of this method which helps in discussing the validity of results.