Classifications of subjects with the language PROLOG

The logical language PROLOG is used for the definition and characterization of groups of subjects. The groups are firstly defined by sets of variables with comparable scales. Secondly, the single members of the groups are characterized by logically structured combinations of variables which do not necessarily have comparable scales. The performance of the characterizations is estimated by determining the rates sensitivity and specificity. The new classification method is applied in a follow-up study including the assessment of the activity of 76 healthy subjects during two controlled experiments. The classification with PROLOG is then compared with the methods of logistic regression and with discriminant analysis. The comparisons demonstrate that, under similar conditions, the results of a classification with PROLOG parallel the results of statistically based classification procedures. In addition, PROLOG permits characterizations of single subjects based on variables from different scientific disciplines.