According to an aspect, there is provided a method of determining the respiration rate of a subject, the method comprising obtaining a signal from a sensor that is worn or carried by the subject analyzing the signal to determine a plurality of values for a breathing-related feature forming a histogram from the plurality of values for the breathing- related feature, the histogram comprising a plurality of groups, with each group having an associated count that is the number of occurrences of a value or values for the breathing-related feature corresponding to the group applying a weighting to the count associated with each group to form weighted counts and determining the respiration rate from a mean of the histogram with the weighted counts.
