A system comprising: a plurality of sensors (132, 134, 138) for measuring a physiological parameter; and a controller comprising a memory and a processor, wherein the memory stores instructions that are executable by the processor to cause the controller to perform operations comprising: receiving, from a first sensor of the plurality of sensors, first sensor data indicative of the physiological parameter; receiving, from a second sensor of the plurality of sensors, second sensor data indicative of the physiological parameter; correlating the first sensor data and the second sensor data to provide correlated data, wherein the correlated data is indicative of the physiological parameter; determining a health state based on the correlated data; and providing an indication based on the determined health state; characterized in that: at least one sensor of the plurality of sensors is configured for removable attachment to a respective location on an exterior surface of a living body; and correlating the first sensor data and the second sensor data includes weighting each of the first sensor data and the second sensor data based on an operational age of the respective sensor. a plurality of sensors (132, 134, 138) for measuring a physiological parameter; and a controller comprising a memory and a processor, wherein the memory stores instructions that are executable by the processor to cause the controller to perform operations comprising: receiving, from a first sensor of the plurality of sensors, first sensor data indicative of the physiological parameter; receiving, from a second sensor of the plurality of sensors, second sensor data indicative of the physiological parameter; correlating the first sensor data and the second sensor data to provide correlated data, wherein the correlated data is indicative of the physiological parameter; determining a health state based on the correlated data; and providing an indication based on the determined health state; receiving, from a first sensor of the plurality of sensors, first sensor data indicative of the physiological parameter; receiving, from a second sensor of the plurality of sensors, second sensor data indicative of the physiological parameter; correlating the first sensor data and the second sensor data to provide correlated data, wherein the correlated data is indicative of the physiological parameter; determining a health state based on the correlated data; and providing an indication based on the determined health state; characterized in that: at least one sensor of the plurality of sensors is configured for removable attachment to a respective location on an exterior surface of a living body; and correlating the first sensor data and the second sensor data includes weighting each of the first sensor data and the second sensor data based on an operational age of the respective sensor. at least one sensor of the plurality of sensors is configured for removable attachment to a respective location on an exterior surface of a living body; and correlating the first sensor data and the second sensor data includes weighting each of the first sensor data and the second sensor data based on an operational age of the respective sensor.