Every 2 seconds of the signal is tested for on head or off head. When the recording is completed, the total duration of the off head portion is computed and displayed as ‘off head’ metric.
How to read it
Values from 0 to 10 are acceptable, and the Record Quality metric should be inspected next. Any values above 10 should be considered substantial record loss, and intervention should be given with the subject to minimize durations of complete EEG signal loss.