In embodiments of the present invention, periodic data is analysed by obtaining (S1) a vector of delay coordinates for each one of a plurality of samples of the periodic data in a time window, and transforming (S2) each of the vectors into a coordinate system comprising a plurality of predefined vectors, to obtain a projection of an attractor of the periodic data along one of the predefined vectors. The periodic data may be physiological data. In-formation representing one or more characteristics of the obtained attractor, which is of diagnostic value, is then displayed (S3) to enable a diagnosis.
