A system for identifying a change in walking speed of a person includes plurality of sensors (8,9,10,11,18) disposed among a plurality of locations in a living space (20). Each of the plurality of sensors (8,9,10,11,18) is operable to detect one of motion of the person or location of the person. Travel times (tt) for a path (19) traveled by the person through the living space (20) are measured based on the signals of the plurality of sensors (8,9,10,11,18). A reliability indication (R1) of the likelihood that another person is visiting the living space (20) is established. A change in the person's walking speed is identified by identifying changes in the travel times (tt), disregarding travel times (tt) which are indicated as unreliable by the reliability indication (R1).
