A computer implemented method and system is used for evaluating an intensive EEG or an EEG during anaesthesia. Time domain and/or frequency range parameters are determined from the EEG graphs. The determined parameters are used in multivariate classification functions and the intensive EEG or EEG during anaesthesia are automatically divided into stages. The EEG graphs are also analysed for interfering signal components from the quantity of biosignals of graphs characteristic of intensive EEGs or EEGs which are not performed during anaesthesia. If interfering signal components are identified, the existence of biosignals of graphs characteristic of intensive EEGs or EEGs which are not performed during anaesthesia is verified by artifact analysis in the absence of artifacts, and is not verified if artifacts are identified.
