A method, apparatus, and system for determining a correspondence of physiological data obtained in a physiological study of a subject. The method includes extracting a first signal from the physiological study. A second signal from the physiological study is also extracted. The first signal and the second signal are obtained by one or more biometric sensors. Data of the first signal and data of the second signal are stored on a memory storage. A coherency value is determined between components of the extracted first signal and components of the extracted second signal. And the correspondence of the physiological study data is determined based on the determined coherency value.
