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Sleep Monitoring/Polysomnography/Signal Quality/SHHS1
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.
Sleep Monitoring/Polysomnography/Signal Quality/SHHS2
Overall study grade as assigned by scorer. These codes reflected the total duration of useable (artifact free, scorable) signals during sleep time across channels, weighing those signals most critical for accurate scoring of respiratory events and staging during sleep time. The Quality Assessment Form for SHHS2 was modified so that the overall quality grade and the signal quality codes were based on signals during sleep time. Since events were only scored during sleep time this provided a more accurate assessment of signal quality during the actual time or scoring. This change would only have affected the quality grade of a small number of studies in SHHS1 where there was a significant amount of time awake with very good signals combined with very poor signals that occurred during sleep. The overall and signal quality grades are comparable between SHHS1 and SHHS2.
The normalized sample weight is the overall normalized, calibrated, trimmed, nonresponse adjusted (household and person-level) reciprocal of a participant's probability of selection into the HCHS/SOL study. The base sample weights, i.e. the reciprocal of a participant's probability of selection into the HCHS/SOL study, were first adjusted by household-level and person-level non-response. The non-response adjusted sample weights were then trimmed using the selected average percentile that minimizes model MSE within each field center. All sample weights that fell above the selected percentile were trimmed to the selected percentile and the trimmed difference was evenly distributed among all of the non-trimmed sample weights. The trimmed, non-response adjusted sample weights were then calibrated using first the 7-category Hispanic Background distribution and then the 12-category age group/gender distribution using the 2010 Decennial Census. Finally, these calibrated, trimmed, non-response adjusted sample weights were normalized using the weighted mean divided by weighted standard deviation of the entire HCHS/SOL sample to normalize the expanded calibrated sample weights (WEIGHT_Final_Norm_Overall). This final sample weight variable is used for analyses purposes only.
Clinical Data/Vital Signs/Seated Blood Pressure
Ankle Brachial Index (ABI) is the average ankle to arm systolic pressures as measured from the left and right sides. The higher of the two ankle measures on the same side is divided by the higher of the two systolic arm pressures to derive the right and left side ABI values. The overall ABI is the mean of those two measurements.