A method for estimating respiratory rate comprises gathering data related to pulse wave in an electrical form, extracting a good quality beat series with proper noise removal and interpolated beats for missing beats, extracting four primary sub-signals and two derived sub-signals from the beat series, performing both time and frequency domain analysis independently for each of the aforementioned six sub-signals and combining the results of the time and frequency domain analysis independently for each sub-signal thus obtaining a group of estimates (2 x 6) for the respiratory rate. The estimating of the respiratory rate is then calculated by removing sub-signal estimates with poor signal-to-noise ratio and those that are statistical outliers.
