A physiological monitoring system may determine physiological information, such as physiological rate information, from a physiological signal. The system may receive a calculated value indicative of a period associated with a physiological rate. The system may determine a first value indicative of a baseline of the physiological signal and a second value indicative of a deviation of the physiological signal from the baseline. The first value may, for example, be a median value, an average, or a coefficient corresponding to a best fit curve of the physiological signal. The second value may be a standard deviation value, a standard error, or a root mean square value based on the physiological signal. The system may qualify or disqualify the calculated value based on the first and second values.