[General viewpoints in evaluating findings and making diagnostic decisions]

The process of diagnosis consists of establishment of findings, interpretation of findings and diagnostic decision. The general situation concerning decision is characterized by the fact that incorrect decisions may appear by falsely positive and falsely negative findings. On this assumption a diagnosis can only be confirmed with certain probability or excluded. Unequivocal decisions may be regarded as borderline cases of this situation concerning the decision. Their prerequisites are explained with the help of four-field table and diagrams belonging to this. If these conditions are not given, so that only a probable diagnosis can be made, then the indexes allow of an estimation of the degree of certainty of the evidence. By means of statistical models helps for decision can be obtained. The example of the Bayes-theorem is illustrated with the help of diagrams. In recent years another approach gathers momentum. The methods in question are so-called unclear approaches of the analysis of processes. They essentially support themselves on assessments by experts and on a programmed approach.