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overall_shhs1
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Sleep Monitoring/Polysomnography/Signal Quality/SHHS1
in
SHHS variables
Overall study grade as assigned by scorer. The overall quality grade is based on the quality and duration of EEG, respiratory and oximetry signals. Based on signal quality during recording time. Studies are given a study code varying from outstanding to fair. If interested in studies of the best quality, overall quality scores of Very Good, Excellent and Oustanding can be selected. This code reflects the total duration of useable (artifact free, scorable) signals across channels, weighing those signals most critical for accurate scoring of respiratory events and staging.
quoxim
under
Sleep Monitoring/Polysomnography/Signal Quality/SHHS2
in
SHHS variables
Sleep Heart Health Study Visit 2 (SHHS2)-These vary from 1 (poorest) to 5 (best) and reflect the proportion of sleep time the signals were useable. Useable respiratory data is defined as the number of hours that abnormal breaths can be distinguished from normal breaths.
respevpr
under
Sleep Monitoring/Polysomnography/Signal Quality
in
CHAT variables
1=Problems with respiratory events (when due to the technical quality of the respiratory signals, distinctions between hypopneas and normal breaths are equivocal in over 20 % of scored events; also when the quality of the oximetry signal raises doubts about actual magnitude of desaturation linked with over 20 % of respiratory events (unstable baseline)