Abstract: A computer implemented method for determining accuracy of heart rate variability is proposed. The method comprises the following steps: a) providing at least one photoplethysmogram obtained by at least one portable photoplethysmogram device (110); b) Determining at least one signal feature by evaluating the photoplethysmogram; c) Determining the accuracy of heart rate variability by using at least one trained model, wherein the signal features determined in step b) are used as input for the trained model.

Abstract: A method and device for determining the influence of activity of a user on a health level of a user is disclosed. It is based on measuring the heartbeat signal of the user using a heartbeat sensor (10) and calculating a health level (H) of the user depending on the heart rate variability of the user. Further, a motion signal of the user is measured using an acceleration sensor (16). Several activity parameters (Pi) are calculated. A first activity parameter (P I) depends on the amount of sleep of the user. A second activity parameter (P2) depends on the amount of steps taken by the user. Further activity parameters may be used. From this data, a fitting function is used to determine coefficients (Ci) indicative of how strongly the health level (H) depends on each of the activity parameters. The heartbeat sensor (10) can include an optical reflection sensor.